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Widely distributed throughout North America, the cabbage looper (Trichoplusia ni) adult is a gray moth with a silvery V-shaped spot in the middle of each forewing with a wingspan of 1 ½ to 2 inches. The moths fly at night so most people rarely notice them.
Larvae are easily identified by their unique movement in which they double up or “loop” as they inch along. Also called “inchworms”, cabbage looper larvae are large (about 1 ½ inch), pale green caterpillars with a pair of narrow white lines down their backs and one line along each side. Eggs are light green, dome shaped and generally found on the underside of leaves..
Moths emerge from overwintering pupae in mid-spring and lay their eggs on the lower surface of leaves. Eggs hatch in 3-6 days and the larvae feed for 2-4 weeks, then pupate for about 10 days in thin silky cocoons attached to stems or leaves and the new adults emerge. There are three to four generations per year in most areas.
Cabbage looper are common pests of the brassica family of plants, including cabbage, kale, collards, cauliflower, broccoli, turnips, Brussels sprout, kohlrabi, mustard, watercress and others, yet host plants are not restricted to only cole crops; other plant hosts include tomato, cucumber, potato, beet, bean, celery, lettuce, pea, parsley, spinach; flowers include carnation, and nasturtium.
Damage and Signs of Infestation
Larvae have voracious appetites making an “infestation” mean as few as 2 or 3 worms per plant. Cabbage loopers chew large, irregular holes in the leaves of host plants. As they feed they may bore into the center of heads and contaminate them with their fairly noticeable dark green fecal pellets.
A serious infestation can deprive a plant of photosynthesis owing to the absence of leaves, resulting in the death of the plant. A minor infestation will look unsightly but crops may still be edible.
Organic Control and Prevention of Cabbage Looper
1. Use row covers: Growing crops under floating row covers is an excellent and essential method of preventing cabbage looper adults and other pests from laying their eggs on plants. These row covers create a barrier that allows air, light and moisture through but keep insects out.
2. Scout and handpick: Keep a close lookout for caterpillars, eggs, or signs of damage (chewed leaves, dark green droppings). You can easily keep small populations of cabbage loopers under control by picking them off your plants and dropping them in a bucket of soapy water.
3. Cultural practices: Cleaning up after a harvest, tilling the soil and removing dead plants and garden litter can reduce number of overwintering pests in the garden. Another way to avoid serious infestations is to stagger (earlier or later) your planting dates in a manner to avoid crop susceptibility depending on your growing season.
4. Grow healthy organic plants: Strong plants can handle some cabbage looper damage better than weak, struggling plants which is of course a no brainer. Ensuring that your crops are getting enough sunlight and water and that the soil is well-drained and rich in nutrients and organic matter will help minimize damage caused by pests.
5. Biological insecticides: Bt (Bacillus thuringiensis) has been used for suppressing cabbage loopers for a long time now, and has the advantage of not disrupting beneficial insect population. Bt is a naturally occurring bacterium that is fatal to only caterpillars. Spinosad, a biological pesticide is another bacterium that works as a neurotoxin when ingested by many insects including cabbage looper caterpillars.
6. Attract beneficial insects and natural predators: Planting flowers, such as marigolds, calendula, sunflower, daisy, alyssum, or dill can attract beneficial insects such as native parasitic wasps and trichogramma wasps that parasitize cabbage looper eggs. Birds, spiders and predatory beetles will also help in controlling these pests. If you have chickens or ducks, allow them to forage for cabbage loopers once your plants have been established.
7. Red-leafed varieties of cabbage and kohlrabi are less preferred by cabbage loopers, probably because they provide insufficient camouflage.
8. Organic sprays and soaps: Homemade hot pepper spray and garlic sprays have been known to work to some effect. Organic insecticidal soaps will help kill caterpillars but must be applied extensively to achieve good control.
If your plant leaves appear like a kid was doodling squiggly lines, you have leafminers. Leafminers are larval (maggot) stage of insects that live in and eat the leaf tissue of plants. They appear in spring, like young robins and daffodils, but are nowhere near as welcome. The vast majority of leaf-mining insects are moths (Lepidoptera), sawflies (Hymenoptera), flies (Diptera), though beetles (Coleoptera) also exhibit this behavior.
Host plants include apple, beans, beets, blackberries, cabbage, citrus plants, Swiss chard, lettuce, garlic, peppers, tomatoes, onions, spinach and a variety of ornamental flowers especially chrysanthemum and nasturtium, trees and shrubs.
On vegetable crops, the most common leafminers belong to the genus Liriomyza.
Adults are small (1/10th of an inch or 2.5 mm long) black and yellow flies with clear wings and are similar in appearance to small, hunch-back house flies. Sometimes the flies are more silvery-gray in color than black.
The only leafminers that lay masses of eggs on the underside of leaves in gardens are Pegomya fly species (Anthomyiidae), on Amaranthaceae (spinach, chard, etc.) and Polygonaceae (docks, garden sorrel; occasionally rhubarb, but the larvae always seem to die pretty quickly in rhubarb leaves). All agromyzid flies (such as Liriomyza) insert their eggs in plant tissue, and these are impossible to see, although sometimes you can see discolored spots where the female inserted her ovipositor. They are tiny, cream-colored and oval.
The larvae of leafminers are bright yellow or pale green, stubby, translucent maggots that are about 2 mm long when they emerge from the leaves to pupate. Pupae look like tiny brown grains of rice. Leaf-mining flies though, don’t make cocoons.
Adults emerge from overwintering cocoons in early spring and lay their eggs in clusters just under the surface of the leaf epidermis. The larvae mine leaves for 1 to 3 weeks till mature, then drops down to the soil and pupates for 2 to 4 weeks. There are normally 2 to 3 generations per year; more in greenhouses.
Larvae mine between upper and lower leaf surfaces, creating winding, whitish tunnels that are initially narrow, but then widen as the larvae grow. This may cause leaves to dry out, resulting in sun-burning of fruit and reduction and yield and quality. Excessive damage from larvae on young plants and seedlings can cause them to die due to lack of chlorophyll and reduced photosynthesis.
Mines and feeding punctures also open up ways for pathogenic organisms to enter. Excessive leaf mining may cause death of the plant.
Organic Control and Prevention of Leafminers
1. Check your transplants for leaf mining damage before planting them out in your vegetable garden.
2. Cover plants with floating row covers to keep adults from laying eggs on leaves. Protect small seedlings by covering them with a protective cloth or a cold cap.
3. Pick off and destroy infested leaves.
4. Do not plant vegetables in areas where you’ve had previous leafminer infestations.
5. Cut forage crops, remove remaining old plants and till the ground after harvesting your crops. This can significantly reduce leafminer populations by destroying pupae in the soil and eliminating several sources.
6. Scout for egg clusters on susceptible plants regularly and destroy them as soon as they are visible.
7. If available, plant vegetables varieties that are less susceptible to leafminer infestation, such as tomato with curled leaves.
8. Leafminers on vegetable crops have been kept under control by their natural enemies, in particular parasitic wasps such as Diglyphus begini and Chrysocharis parksi. These wasps feed on leafminer larvae and can significantly reduce leafminer populations. Diglyphus isaea is a commercially available beneficial insect that will kill leafminer larvae. Encourage these parasitic wasps by planting nectar-and pollen-rich flowers such as dill and yarrow.
9. Leafminer infestation can be reduced or prevented by planting trap crops near the plants to be protected. Lamb’s-quarter, columbine and velvetleaf will distract leafminers, drawing them to these plants and thereby reducing the incidence of attacks on nearby crops.
10. Spray infected plants with Spinosad, an organic insecticide, which will control the leafminer. Spinosad does not kill on contact but will have to be ingested by the leafminer to take effect.
11. Spray Neem oil to control or prevent leafminer infestations. Neem oil will break the leafminer’s life-cycle by preventing larvae from reaching maturity. It also acts as an anti-feedant, a repellant and it interferes with egg laying activities.
12. Use sticky yellow traps to catch egg laying adults.
13. Cover the soil under infested plants with plastic mulch to prevent the larvae from dropping down into the soil and pupating.
14. If using trap crops to distract leafminers is not on your agenda, control weeds such as lamb’s-quarter and dock which are known leafminer hosts.
Common Names: Spittlebug, Froghopper
If you spot little blobs of foam or mass of bubbles on your plants, the culprit is most definitely- spittlebug nymphs. Contrary to popular belief, the foam isn’t really spit. Spittlebug nymphs suck plant juices like aphids, but they remove so much water and carbohydrates that excess fluid is produced.
They cover themselves with this fluid and then produce the spittle by bubbling air from the tip of the abdomen into the liquid. The froth serves a number of purposes. It hides the nymph from the view of predators and parasites, it insulates against heat and cold, thus providing thermal control and also moisture control. Without the froth the insect would quickly dry up.
Adults are oval, frog-faced, and 6 to 10 mm long. They are tan, mottled brown, or black and are similar to leafhoppers in appearance but stouter, with sharp spines on the hind legs. Adults are very active and jump when disturbed. Nymphs are yellow to yellow-green in color, look similar to adults but are wingless, and can be found inside the foamy mass of “spittle.” Eggs are white to beige in color.
Overwintering eggs hatch in spring (mid-April), and nymphs develop for 6-7 weeks in spittle masses on plant stems. Adults feed throughout summer and start to lay overwintering eggs in rows on stems or stubble by early fall, around September.
Strawberry, legume forage crops such as clover and alfalfa, many ornamental and nursery plants including junipers and pine trees.
Spittlebugs are rarely a serious problem in home gardens simply causing an unsightly mess. In crop plants however, adults and nymphs suck plant juices, causing stunted, dwarfed, and weakened plants with reduced yields. Adults migrate in large numbers from hay fields to nearby crops when hay is cut; this is when home gardens can be suddenly infested.
Organic Control and Prevention of Spittlebugs
1. Cultural control: Spittlebug eggs overwinter in old garden debris and other such areas so a good garden clean up ridding of old plant material before the start of every growing season will considerably limit the numbers that hatch. Make a point to till under stubble of foliage legumes in the fall as they are usually found there.
2. Monitor, handpick and spray: Keep a keen eye out for spittlebug patches and when you detect them, spray a direct stream of water on the patches to dislodge as many nymphs as possible. Light accessible infestations can be removed by hand or by a strong water spray.
3. Row covers: Spittlebugs are fond of grasses, so when nearby hay fields are cut, make sure to cover your susceptible garden plants with a floating row cover.
4. Homemade spray: A garlic or hot based organic homemade insecticide works well for spittlebugs. Using both garlic and peppers, you can do a double whammy on them! Puree peppers, garlic and water together. Let it sit for a day. Strain and mix in an organic liquid soap. Wipe the foam off your plants and spray this mixture. Always test a little of this mixture on a portion of the plant first to ensure that it will not harm it. Also, don’t apply such mixtures on a hot or sunny day, as the plant could burn and ultimately die.
5. Predatory insects: There isn’t any known effective natural control for spittlebugs but praying mantises prey on most insects that you would hate, so they would be your best bet. Order a case of them or attract them to your garden.
6. Plant based oils: Use neem oil or a citrus based oil to control and prevent insect infestations. They usually act as feeding deterrents and help disrupt normal bug activity.
7. Organic insecticidal soap: Several organic insecticidal soaps are available in the market that help control and rid of spittlebugs along with several other pests, Insecticidal Soap Concentrate being one of them. This organic soap contains potassium salts of fatty acids which help break down insect outer shell and cause dehydration and loss of body fluids.
Common name: Pickleworm
Scientific name: Diaphanis nitidalis
Pickleworms are tropical insects and cannot tolerate cold temperatures. These pests are predominant in the southeastern United States, ranging as far north as Connecticut, Illinois, Iowa, Kansas and New York. They overwinter in Florida and Texas, where they may be active year round. They are known to spread northward late in the season.
Lifecycle and Description
Adults: The pickleworm adult moth is a small flashy moth with wide triangular wings and a wingspan of 1 ¼ inches. The wings are mostly iridescent brown with a central band of semi-transparent yellow. The tip of the abdomen contains a cluster of brush-like hairs. Pickleworm moths are generally inactive during the day and peak flight activity occurs typically 3-5 hours after sundown.
Eggs: Adult moths lay tiny eggs directly on growing areas of the plant, such as new leaf buds, flowers and shoots. Eggs are white initially, but change to yellow as they mature. Eggs hatch in about 4 days.
Larvae: The young larvae of pickleworms are thin white caterpillars with numerous black spots. As they mature though, they get plump and darker in color while losing their spots. Color is dependant largely on the insect’s food source. When mature, larvae often attain a length of 1 inch. Pickleworms undergo 5 larval instars before pupating.
Pupae: Pupation usually occurs in a leaf fold, and dead, dry leaf material is used. Pupae are brown and about ½ inch long.
A pickleworm can complete its life cycle in 30 days and there can be up to 4 generations a year.
Pickleworms feed on both wild and cultivated cucurbit species. Creeping cucumber, Melothria pendula, is an important wild host. Cucumber, pumpkin, muskmelon, cantaloupe and squash are the common hosts of pickleworms. Among all cucurbits, summer squash is the most preferred, and the most heavily damaged.
Primary concern with pickleworms is damage to the fruit. Pickleworm larvae do however, feed on, and tunnel into, flowers, vines and fruit. Young pickleworms usually feed for some time among small leaves at the growing tips of vines or within blossoms. Growing vines can get riddled with holes and cease to grow. As pickleworms grow they bore into fruit and continue to feed, causing internal damage to fruit. Entry holes are marked with a pile of white frass. Damaged fruit usually sours, spoils and rots.
Organic Control and Prevention of Pickleworms
1. Early planting: Early-planting enables growers to harvest most of the crop before the pickleworm can cause excessive losses. Very early spring plantings are seldom damaged.
2. Trap crop: Squash could be used as a trap crop to keep pickleworm from attacking other cucurbits, as squash is the preferred host of pickleworms.
3. Screen covers: The use of floating row covers has been shown to be effective against pickleworm moths and other insects from laying eggs on the plants. Row covers should be applied immediately after planting; however, they must be removed when plants begin to flower to allow for pollination.
4. Sanitation and weed control: Removal and destruction of infested plants including vines and fruit following harvest is a good cultural practice to reduce populations. Keeping the surroundings clean and weed-free can go a long way in preventing pickleworms from overwintering in and around your garden.
5. Fruit bagging: An experiment carried out in the field to test the efficacy of paper bags for protecting cucumber fruits against pickleworm penetration showed that paper bagging is 50% more effective than conventional insecticide! In addition, the color and size of the fruit were not altered by bagging.
6. Use of resistant varieties: The following varieties have demonstrated marked resistance to pickleworms: Butternut 23, Summer Crookneck, Early Prolific Straightneck and Early Yellow Summer Crookneck. Beware; the following varieties are more susceptible to pickleworms: Cozini, Zucchini, Black Zucchini Caserta, Shrot Cofozella and Benning Green Tint Scallop.
7. Monitor and handpick: Scout regularly for eggs among your cucurbits. Infested stems can be slit horizontally and the pickleworms can be removed. Soil should be placed over the injured stem to encourage rooting.
8. Natural predators: Pickleworms have natural enemies such as the soldier beetle, Calosoma beetles, Harpalus beetles, red imported fire ant, trichogramma wasps and braconid wasps that can help control or prevent infestations to an extent.
9. Spraying Bt (Bacillus thuringiensis) or Steinernema carpocapsae, a beneficial nematodes is a great solution according to a vegetable crop specialist at the University of Florida. To control an infestation, spray Bt or beneficial nematodes in the early evening on susceptible plants.
10. Neem and Spinosad: Neem products are botanical insecticides that are effective against a variety of insect pests including pickleworms through contact toxicity, disruption of insect molting and feeding deterrence. Spinosad is derived by microbial fermentation and is effective against pickleworms while being safe to most beneficial insects.
Buy Grub Control, a unique organic formulation that can be used as preventative or early treatment against young active larvae. In need of some horticultural oil for organic insect and disease protection? Neem oil may just be the what you need.
Mealybugs are insects in the family Pseudococcidae, unarmored scale insects found in moist, warm climates. They are considered pests as they feed on plant juices of greenhouse plants, house plants and subtropical trees and also act as a vector for several plant diseases. There are approximately 275 species of mealybugs known to occur throughout the United States.
Mealybugs are very small (about an eighth of an inch long), oval-shaped flightless bugs that have a white powdery appearance and infest both indoor and outdoor plants. They move slowly, when they move at all. Mealybugs are soft-bodied insects, but they secrete a powdery wax layer over themselves. This protective layer gives them their name, as it makes them look as though they’ve been coated in meal or flour. It is also what makes them quite hard to kill.
Mealybug infestations appear on plants as fuzzy, white cottony-looking mass around the stems and leaf nodes. Female mealybugs hide their eggs in this fluffy white excretion and can deposit 300-600 eggs within their compact, cottony mass.
Eggs hatch in 1-3 weeks and small active yellow nymphs move all over the plant in search of feeding sites in which to settle in. As they feed, they secrete honeydew and a waxy coating begins to form over their bodies. Nymphs spend 4-8 weeks developing into the adult form.
Plants they attack
Mealybugs thrive on a wide variety of indoor and outdoor species, including ficus, philodendron, coleus, begonia, citrus plants, fern, dracaena, ivy, poinsettia, cacti and succulents, African violets, bougainvillea, fuchsia, grape vines, hoya, orchids, oleander, passion flower, peach, tomato, potato, pineapple, coffee trees, cassava, papaya, mulberry, sunflower and avocados among others.
Damage and Symptoms
Mealybugs feed on plant sap and generally position themselves under leaves and at stem joints, while they attack the plant with their piercing mouths known as stylets. This penetrative feeding damages the plant by draining its sap and may possibly transmit bacterial and fungal infections. This sap feeding weakens the plant and causes slow plant growth, yellowing and deformed leaves and leaf drop. They also excrete large amounts of sticky ‘honeydew’ that attracts ants and may lead to the growth of sooty mold. Damage is not often significant at low pest levels; however, heavy infestations can kill a plant.
Organic Control and Prevention of Mealybugs
1. The first rule of successfully ridding plants of mealybugs (or any pest for that matter) is to detect and act upon them early. It’s far easier to rid of a small infestation than to eradicate a full-blown attack. Inspect your plants regularly to ensure early detection.
2. The water cure: Isolate the infected plants. Spray as strong a stream of water as the plant can bear. This will dislodge most of the bugs. Kill dislodged bugs, if not already dead. For this to be effective, repeat on a daily basis until the mealybugs are gone.
3. Sanitation and cultural control: It is a good practice to keep your garden and greenhouse clean and void of old and unwanted material. Dead leaves and prunings should be removed as these may have mealybugs or their eggs on them. Do not overwater or over-fertilize as mealybugs are attracted to plants with high nitrogen levels and soft growth.
4. Control ants: Ants feed on the honeydew that mealybugs produce and act as their henchmen by protecting them from predators to ensure their food supply.
5. Organic insecticidal soap: Buy an organic insecticidal soap which utilizes the power of potassium salts of fatty acids that works by weakening the insect’s waxy protective outer shell and spray on infestations. These soaps are generally safe to use on vegetables but always check the label.
6. Rubbing alcohol method: Spot treat mealybug infestations with a cotton ball dipped in rubbing alcohol. Simply dab the critters and rub them away. The alcohol strips away the waxy coating leaving the mealybugs exposed.
7. Organic dishwashing liquid: Any soap will effectively suffocate the mealybugs as the soap coats the bug and also breaks down their protective waxy layer. Just mix the dishwashing soap in water and spray on infestations.
8. Neem oil: Neem oil derived from the neem tree has insecticidal properties in addition to being a fungicide and having systemic benefits.
9. Kitchen insect spray: Combine 1 garlic bulb, 1 small onion and 1 teaspoon of cayenne pepper in a blender. Mix into 1 quart of water and allow it to infuse for an hour. Strain through a cheesecloth and add a tablespoon of organic soap and mix well and spray!
10. Beneficial insects: Beneficial insects and parasites are considered the best long-term solution for mealybug infestations. Ladybirds, lacewings and hover flies kill mealybugs. Parasitic wasps (Leptomastix dactylopii) parasitize mealybug eggs and are an effective method of controlling infestations. There is also a commercially available mealybug predator known as the ‘mealybug destroyer’, which is a small dark brown ladybug (Cryptolaemus montrouzieri) whose preferred food happen to be all the stages of mealybugs.
Thrips are tiny, slender insects with fringed wings that feed on a large variety of plants, by puncturing and sucking up the contents. Common names for thrips include thunderflies, thunderbugs, storm flies, thunderblights, storm bugs and corn lice. There are many different species of thrips (over 5,000), most of which are pests (often in the family Thripidae), while certain species (black hunter thrips and sixspotted thrips) are beneficial predators that feed only on mites and other insects.
Thrips are extremely active, feed in large groups and leap or fly away when disturbed.
Lifecycle and Description
Adults are minute, slender insects with narrow fringed wings and measure about 0.5 mm to 1 mm long. Immatures (called larvae or nymphs) are similarly shaped with a long, narrow abdomen but lack wings. Thrips are not strong fliers but can readily travel long distances by floating with the wind or being transported on infested plants. Most thrips range in color from translucent white or yellowish to dark brown or blackish, depending on the species and life stage.
Adults and pupae overwinter in garden soil, sod, debris and cracks in barks. In spring, emerging females lay eggs in plant tissues including flowers, stems and leaves. Eggs hatch in 3-5 days in warm weather, or in weeks in colder weather. Nymphs feed for 1 to 3 weeks, then depending on the species either drops down to the soil to pupate or pupates on the plant itself. Pupal stage lasts 1 to 2 weeks before adults emerge. There can be 5 to 15 generations a year outdoors and year-round generations in greenhouses.
Thrips have been found on various plant orders showing their wide host plant range including various berries, field crops, forage crops, grass flowers, legumes, peonies, privet hedges, roses, trees, truck crops, vines and weeds. They are known to cause damage to avocado, beans, citrus and blueberry plants, figs, azalea, hypericum, photinia, rhododendron, garlic, onion, pepper, carrot, squash, gladioli, toyon, impatiens, petunia, cucurbits, grapes, strawberry, stone fruit among others. They seem to prefer grasses and yellow or light-colored blossoms.
Thrips, both adults and nymphs cause damage to the plant by piercing and sucking out cells on the leaf surface, leaving a silvery stippling or streaking on leaves. Severe thrip infestations can stunt and distort plants, damage flowers and scar fruit. Some species are responsible for spreading tomato spotted wilt virus (TSWV) and impatiens necrotic spot virus (INSV).
Organic Control and Prevention of Thrips
Producing thrips-free crops requires a multi-faceted approach, as with many other pests.
1. Eliminate sources: Remove weeds and grass from in and around your garden areas to eliminate alternate hosts for thrips. Remove and dispose of old, spent flowers after your harvest. Proper disposal of plant residues is also important.
2. Start and stay clean: An important part of keeping your crops void of thrips is to make sure the young plants are clean. Examine purchased plants or transplants for thrips before placing them in your greenhouse or garden. Covering openings to greenhouses has found to reduce pest problems by up to 70%. Vigorous healthy plants normally outgrow thrips damage, but excessive use of nitrogen fertilizers may promote higher populations of thrips.
3. Monitor: The most reliable way to detect thrips is with a yellow or blue sticky trap. Branch beating or shaking foliage or flowers onto a sheet of paper or a beating tray or sheet can help monitor and rid of a few thrips. Hosing down thrips from infested plants does help reduce pest numbers to a certain extent.
4. Row covers: Row covers, hot caps, and other types of cages can exclude thrips and other pests from vegetables and other young herbaceous plants. Basically, any type of covering that excludes insects but allows light and air penetration can be used.
5. Reflective mulch: Reflective mulch is said to confuse and repel flying insects that are searching for plants because the reflected ultraviolet light interferes with the insect’s ability to locate plants. This is more effective during early growth when plants are small and do not cover the mulch. Reflective mulch has been shown to delay or sometimes even prevent pests such as winged aphids, thrips, leafhoppers and whiteflies.
6. Pruning: Prune and destroy injured and thrips infested terminals of plants. Shearing is not recommended though as it stimulates new susceptible growth. Instead, prune by cutting plants just above branch crotches and nodes.
7. Beneficial insects: Release commercially available natural predators to prey on thrips such as minute pirate bugs, damsel bugs, ladybugs, lacewings, predatory mites (Amblyseius cucumeris) and parasitic wasps or attract them to your garden by planting alfalfa, goldenrod and yarrow.
8. Biological insecticides: Biological insecticides such as Beauvaria bassiana and Verticillium lecanii are an effective strategy against thrips. Both are fungi that grow naturally in soils and are proven to help rid of thrips and many other pests. Spinosad insecticide is based on a compound found in a bacterial species and it helps kill thrips among several others.
9. Soaps and oils: Spray a safe organic insecticidal soap or horticultural oil such as neem oil on afflicted plants to aid with thrips control.
Common name: Melonworm
Scientific name: Diaphania hyalinata
Melonworms are tropical insects and cannot tolerate cold temperatures. They occur throughout most of Central and South America, the Caribbean, south Florida and south Texas where they live year-round. The melon
worm travels northward during the summer months where it can be found in the southeastern states, though occasionally it disperses north to New England and the Great Lakes region. Melonworms, however, are rarely found north of the Gulf states.
Lifecycle and Description
Adults: The melonworm moth has a brown head and white-tipped abdomen with bushy hair-like tufts. Their wings are white, slightly iridescent centrally and are edged with a broad band of dark brown. Wingspan of the melonworm moth is about an inch. Melonworm moths are active in the night.
Eggs: Melonworm moths deposit oval, flattened eggs in small clusters of about 2-6 eggs. Eggs are generally deposited on buds, stems, and underside of leaves of host plant. Initially they are white or green but gradually turn yellow. Eggs hatch in 3-4 days.
Larvae: Newly hatched melonworm larvae lack color, but turn pale yellow-green colored in a few days. Melonworm larvae build silk or cocoon-like nests under leaves where they rest or hide in during the day while continuing to feed on foliage. Mature melonworm larvae are dark green with 2 lateral white stripes that are their most distinctive characteristic. The stripes fade or disappear prior to pupation.
Pupae: Prior to pupation, larvae spin a loose cocoon on the host plant, often folding a section of the leaf for added shelter. Pupa is light to dark brown color, measures about 15 mm in length and lasts about 9-10 days.
A melonworm can complete its life cycle in 30 days and there can be up to 4 generations a year.
Melonworms are restricted to feeding on cucurbits; both wild and cultivated species may be attacked. They prefer feeding on summer squash and winter squash. Pumpkin is of variable quality as a host, while cucumbers, gherkins and cantaloupes are attacked, but not preferred. Watermelon is a rare host.
Melonworm damage is mainly on foliage, especially if foliage of preferred host is available. Usually the leaf veins are left intact, resulting in a lace-like appearance. If foliage is exhausted, or if the plant is a less favored species, the larvae may feed on the surface of the fruit or even burrow into the fruit. Hence melonworm larvae are popularly called ‘rindworms’ among growers because they cause scars on the surface of melons.
Organic Control and Prevention of Melonworms
1. Early planting: Early-planting enables growers to harvest most of the crop before the melonworm can cause excessive losses. Very early spring plantings are seldom damaged.
2. Trap crop: Squash could be used as a trap crop to keep pickleworm from attacking other cucurbits, as squash is the preferred host of melonworms.
3. Screen covers: The use of floating row covers has been shown to be effective against melonworm moths and other insects from laying eggs on the plants. Row covers should be applied immediately after planting; however, they must be removed when plants begin to flower to allow for pollination.
4. Sanitation and weed control: Removal and destruction of infested plants including vines and fruit following harvest is a good cultural practice to reduce populations. Keeping the surroundings clean and weed-free can go a long way in preventing pickleworms from overwintering in and around your garden.
5. Fruit bagging: Although melonworms rarely bore into fruit, protecting fruit with a layer of paper bag or plastic will definitely help.
6. Monitor and handpick: Scout regularly for eggs and larvae among your cucurbits. Melonworm larvae feed mainly on foliage and can be easily spotted underneath leaves nestling in their silken cocoons.
7. Natural predators: Melonworms have natural enemies such as the soldier beetle, Calosoma beetles, Harpalus beetles, red imported fire ant, trichogramma wasps and braconid wasps that can help control or prevent infestations to an extent.
8. Spraying Bt (Bacillus thuringiensis) or Steinernema carpocapsae, a beneficial nematode is a great solution according to a vegetable crop specialist at the University of Florida. To control an infestation, spray Bt or beneficial nematodes in the early evening on susceptible plants.
9. Neem and Spinosad: Neem products are botanical insecticides that are effective against a variety of insect pests including pickleworms through contact toxicity, disruption of insect molting and feeding deterrence. Spinosad is derived by microbial fermentation and is effective against melonworms while being safe to most beneficial insects.
The harlequin bug (Murgantia histrionica), also known as calico bug, fire bug or harlequin cabbage bug is a black stinkbug that is particularly destructive to cabbage and related plants in tropical America as well as throughout most of North America, especially the warmer parts of United States.
In addition to cabbage, harlequin bugs can be a major pest of broccoli, radishes, kale, collards, mustard, turnips, Brussels sprouts and cauliflower. They may also attack corn, tomatoes, okra, squash, asparagus and beans.
Both adults and nymphs cause damage to stems, leaves, fruits and seeds. They use their piercing mouthparts to inflict damage and suck away plant sap. Damage on leaves and stem look like uneven discolored spots. Young plants if left unchecked, will wilt, turn brown and eventually die. Mature plants will have their growth stunted. Damage on fruits will appear as dark holes or white-yellowish spots.
Symptoms include cloudy areas around the point of extraction, browning and wilting plants, and slower plant growth.
Adult harlequin bugs are attractive shield-shaped shiny black insects with bright red, yellow or orange markings. They measure about 7-10 mm in length.
Eggs are light colored barrel-shaped, 1 mm long and are laid in clusters in the foliage. Eggs hatch in 5-14 days.
The nymph is oval and similar to adults in appearance and color but slightly smaller and lack wings. Nymphs mature into adults in 5-8 weeks.
Generally 1-3 generations depending on location with warmer places more likely to have more generations.
Organic Control and Prevention of Harlequin Bugs:
1. Grow resistant varieties: Some types of brassica plants are naturally resistant to Harlequin bugs. The following varieties are recommended:
Cabbage: Copenhagen Market 86, Headstart, Savoy Perfect Drumhead, Stein’s Flat Dutch, Early Jersey Wakefield.
Collards: Green Glaze.
Cauliflower: Early Snowball X, Snowball Y.
Radishes: Red Devil, White Icicle, Globemaster, Cherry Belle, Champion, Red Prince.
2. Cultural control: Destroy heavily weeded and bushy areas in and near your garden. Adult stink bugs prefer overwintering in such sites among legumes, blackberries, Russian thistle, mustards and little mallow. Till the growing area, destroy and rid of crop debris and good weed management will help minimize stink bug populations.
3. Monitor and handpick: Harlequin bugs have decent mobility so be prepared. They also release a stink gas when threatened so beware and cover your nose! Remove them and drop them into a bucket of soapy water. Shaking infested plant or tree will send them tumbling down. Growers have successfully controlled harlequin bugs by frequent vacuuming. Spray plants with water to knock them down and kill them off.
4. Plant trap crops: Mustard, millet, buckwheat, sorghum, sunflower, marigolds, lavender and chrysanthemums are good trap crops to attract stink bugs to attack them rather than your crop of interest. Once these trap crops are infested, keep a bag ready to trash the infested plant in.
5. Physical traps: Yellow sticky traps or bucket painted yellow filled with soapy water can rid of quite a few unsuspecting stink bugs. An open pipe painted yellow stuck into the ground can also be used effectively for trapping stink bugs. Then there are commercially available stink bug traps that can be tried out.
6. Beneficial insects include ants, ladybird beetles, minute pirate bugs and some lacewings, all of which destroy stink bug egg masses. Attract these insects by planting several nectar producing flowers. Praying mantises, toads and some birds (including chickens and ducks) would love to feed on some adult Harlequin bugs.
7. Sprinkle diatomaceous earth in your garden and in prone areas. It works by breaking down the waxy protective layer on the stink bugs exoskeleton, eventually causing it to dehydrate.
8. Make a garlic spray and use as frequently as needed. Stink bugs detest the potent smell of garlic and will repel them from your garden.
9. Kaolin, a soft, white silicate clay mineral can be combined with water to form a protective physical powdery barrier that will prevent stink bugs and other pests from feeding on plant tissue.
10. Use an organic insecticidal soap and spray this solution directly on stink bugs or in areas they frequent. The soap kills the bugs by breaking down their protective exterior and dehydrating them.
11. Neem oil is another natural product that can help reduce stink bug populations by disrupting their feeding and mating habits.
12. Companion planting: Plant garlic, tansy, mint, catnip and radish to help repel Harlequin bugs.
Few things irk a tomato gardener more than a promising crop of healthy, juicy tomatoes ruined by fruitworms. The larva of the moth Helicoverpa zea is a major agricultural pest. It can feed on many different plants; hence the species has many common names depending on what the larva is consuming. Tomato fruitworm, when it consumes tomatoes. Cotton bollworm and corn earworm, when it consumes cotton and corn respectively, are its other well known aliases.
Adult moths have yellowish tanned bodies, a tan-colored head and bright green eyes. A solitary dark dot in the middle of each forewing coupled with several dark markings help distinguish them. The hindwings are pale in color and is enveloped by a dark brown border.
The moth lays eggs on the foliage of host plants both on upper and lower surfaces. Eggs are white or cream-colored, slightly flat, spherical shaped that darken before larvae hatch. Depending on the temperature, larvae hatch in 2-10 days.
The larva that hatches from the eggs is yellowish to white in color with a brown head. As the larva matures, its color can change to green, yellow, brown, red or black. Larvae are about 1 ½ inches long, have tan heads and alternating light and dark stripes that run lengthwise on their body. Their skin is coarse and has small, thorn-like projections called tubercles. The voracious larval stage lasts 14-21 days.
When the larvae are done feeding they drop down to the ground, enter the soil and transform into shiny brown pupae. Adult moths emerge from pupae in 10-14 days and start the cycle over. There are 2-5 generations per growing season.
The host plants of tomato fruitworms are a plenty. They love tomato, corn and cotton the most, yet don’t be surprised to see them on eggplant, okra, peppers, soybeans, beans, squash, sunflower and tobacco.
Damage is caused only by the larvae. Although larvae can feed and develop on leaf tissue, the preferred feeding sites in most crops are the reproductive sites, such as tomato fruit and corn ears. On corn, the larvae feed on fresh silk before moving down the ears eating kernels and leaving trails of excrement. In tomatoes, evidence of damage is usually a visible black hole at the base of the fruit stem. They will also eat the flower buds and chew holes in the leaves. It is much the same, though less common, on the other types of plants.
Organic Control and Preventative Measures:
1. Trim tomato plants so that there are no leaves or stems any lower than 12 inches from the ground. This allows ample airflow from ground up and helps keep away many insects from dwelling in your plants and feasting on your precious tomatoes.
2. Look for signs of fruitworm infestations regularly. Adults lay eggs on both sides of leaves, usually close to blossoms. Ridding of eggs can reduce fruitworm populations drastically. Handpick and destroy fruitworm eggs and larvae as you find them.
3. Prevent fruitworms from boring into fruit by covering fruit with fine netting. Better yet, cover plants with floating row-covers to prevent adults from laying eggs on host plants.
4. Avoid growing tomato near corn or any other aforementioned crop, unless your intention is to use them as a trap crop. If one plant gets infested, you could have your garden teeming with fruitworms!
5. Encourage natural predators of the tomato fruitworm. Big-eyed bugs, minute pirate bugs, lacewing and damsel bugs feed on tomato fruitworms. Attract them by planting goldenrod, daisies, alfalfa and stinging nettle. Trichogramma wasps and Hyposoter exiguae wasps parasitize the eggs and larvae respectively. Planting dill, parsley and asters attracts the parasitic Trichogramma wasps. These wasps are available commercially and can be ordered.
6. Bacillus thuringiensis (Bt), a microbial biological control, is effective against tomato fruitworms among several other pests. Use Bt at the first sign of fruitworm eggs. Apply as directed by the product label. Bt works by paralyzing the digestive system and infected fruitworms stop feeding within hours.
7. Neem oil and biodegradable insecticidal soaps have been found to deter fruitworm infestations. Spinosad, a natural, broad-spectrum biological insecticide made from soil microbes works on tomato fruitworms too.
8. Cultural control: Remove and destroy infected plants. Roto-till the soil at the beginning and end of the season to expose and destroy overwintering fruitworm pupae. Rotate crops by planting tomatoes in a different area of your garden each year. Companion planting with garlic has been said to repel many pests.
9. Dusting plants with diatomaceous earth or Rotenone can help deter fruitworms from moving about the plant.
Common Name: Squash Vine Borer
Scientific Name: Melittia cucurbitae
Squash vine borers are one of the most common pests encountered when growing pumpkins or squash. They are a native American insect and are rarely seen west of the Rocky Mountains, but are extremely common in the east. They are diurnal, which means that they are active during the day and are known to prefer laying eggs at sunset.
Adults: Narrow-winged, olive-brown, 1-1 ½ inch moths, with fringed hind legs, clear hind wings, and reddish orange abdomens with black rings. The squash vine borer moth can possibly be mistaken for a bee or wasp because of its movements and bright orange hind-leg scales.
Eggs: Brown, flat, oval. Laid generally singly on the basal stems.
Larvae: Start out as tiny white caterpillars with brown heads. Feed for 4-6 weeks.
Pupae: Silk-lined, black cocoon, ¾inch long. Generally 1-2 inches below the soil surface.
Vines of squash, pumpkin, cucumbers, melons and gourds.
Larvae or squash vine borers chew the inner plant tissue near the base causing vines to wilt, girdle and die off. You can often see a small hole and some frass that looks like sawdust at the base stems.
Organic Control and Prevention of Squash Vine Borers:
Good organic control should involve a combo of several different methods.
1. Cultural practices: Since squash vine borers overwinter in the soil as cocoons, removing spent vines and crop debris after harvesting is a good idea. Till your grow area to destroy any larvae or pupae still present and expose them to natural predators. Avoid planting squash in the same location in the garden season after season.
2. Row covers: Early in the growing season, use floating row covers to keep adult squash vine borer moths from laying eggs. Later when vines start flowering, uncover for pollinators or hand-pollinate. After removing the row covers, use pieces of tulle (wedding net) or aluminum foil to cover any exposed lower sections.
3. Monitoring and handpicking: Keep a close eye on your plants, especially check the stems near the ground. Seek and destroy vine borer eggs. If you see vine borer holes in the stems, one of the only things to do is surgically cut them out. Use a knife to make a slit along the stem (not across!) until you find the culprit or culprits. Remove and kill the caterpillar and cover the cut area of the stem right away with soil or compost to promote rooting.
4. Grow resistant varieties: Butternut squash and other varieties classified as Cucurbita moschata are naturally resistant to squash vine borers. Hubbard type winter squash varieties, yellow summer squash and zucchini, i.e. Cucurbita pepo varieties on the other hand are highly preferred by squash vine borers, and can be used as a trap crop. Another general rule of thumb is that wide hollow stems are preferred to narrow or more solid stems.
5. Color traps: The adult moths are attracted to the color yellow. Surround the garden with small yellow pails half filled with water.
6. Encourage secondary rooting: Heap soil or compost along stems of the plant at several points along the vine choosing nodes where new leaves and sprouts are occurring. This encourages the plant to send more roots into the ground giving rise to a healthy and strong plant that even if attacked by vine borers will not suffer too much damage.
7. Organic insecticides: Spray plants with Bt (Bacillus thuringiensis), concentrating on the stem area to tackle squash vine borers. You can also inject Bt or beneficial nematodes into the stalk where infection is present. These are commercially available, but always seek advice from a local expert to ensure its necessity.
8. Strategic timing: If you have a long growing season, set out transplants as late as possible to avoid the initial swarm of squash vine borers. If the weather permits, try to beat the vine borers by getting a very early crop out before the vine borers emerge.
9. Grow healthy organic plants: Strong, healthy squash plants can manage to give good yields even after taking some damage from vine borers. Ensure that your plants are in a sunny location, in loose, well-drained rich soil with plenty of nutrients and compost.
10. For those who keep chickens or other poultry, allow them to clean up garden patches before the season (after tilling the soil) and at the end of the season.