Click for a hub of Extension resources related to the current COVID-19 situation.
COVID-19 Resources

Green Cloverworm

Article author: Pat Porter
Most recently reviewed by: Suhas Vyavhare (1970)

Common Name(s): Black snout moth, Green Cloverworm

Description

Newly hatched larvae are about 0.5 mm long at hatching and are pale and yellow. Older larvae are light green and have two yellowish-white stripes on the side of the body. Green cloverworms have four pairs of prolegs (three pair under the center of the body and one pair at the end of the abdomen), and this makes them easy to differentiate from soybean loopers because loopers have only two pairs of prolegs. Another distinguishing characteristic is that when disturbed, green cloverworms usually exhibit a rapid flopping or squirming behavior. Loopers do not exhibit this behavior. 

Adults are triangular-shaped and brownish to grayish, about 1 – 1.4 inches in length. They have a relatively long snout. Females have more silver coloration than do males.

Green cloverworm adult.

Green cloverworm adult. Patrick Porter

Origin and Distribution

North America.

Habitat & Hosts

Green cloverworm is a defoliator and capable of removing large amounts of leaf tissue very quickly when present in significant numbers. It is usually a sporadic pest in Texas. Eggs are about 0.5 mm in diameter and are laid singly on the undersides of leaves. Small larvae may only eat the lower tissue of a leaf and leave the upper tissue intact; this is known as skeletonizing. Larger larvae chew all the way through leaf tissue and can eat all of the leaf blade except the larger veins. Green cloverworms are usually not pod feeders, but can damage pods (depending on pod maturity), especially when all available leaf tissue has been consumed. 

Green cloverworm damage to soybean.

Green cloverworm damage to soybean. Patrick Porter

Life Cycle

Green cloverworms have complete metamorphosis. There is an egg stage, six larval stages (instars), a pupal stage and an adult stage. In Texas there are at least three generations per year.  Overwintering occurs along the Gulf Coast.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Significant yield loss in soybean can occur at 20% defoliation in the podfill stage. Control decisions should be made on leaf damage because there are several defoliating pests of soybean and they may all be contributing to yield loss. In addition to green cloverworm, these species can include soybean loopers, cabbage loopers and velvetbean caterpillars. Soybean growers are referred to Managing Soybean Insects in Texas. 

There are several diseases, especially granulosis virus, that help control populations, and beneficial insects (predators and parasitoids) help in control as well. 

Registered insecticides include several pyrethroids like esfenvalerate, cyfluthrin, bifenthrin, zeta-cypermethrin and lambda-cyhalothrin. Other insecticides include carbaryl, spinosad, acephate and methomyl. Bacillus thuringiensis and Beauveria bassiana can be used for control.

Related Publications

Managing Soybean Insects in Texas.

Cotton aphid/Melon aphid

Article author: David Kerns
Most recently reviewed by: Pat Porter (2018)

Common Name(s): Cotton Aphid, Melon Aphid

Pest Location

Row Crop, Vegetable and Fruit

Description

Cotton or melon aphids, Aphis gossypii, are highly variable in size and color, varying from light yellow to dark green or almost black. Although size can vary based on environmental conditions, adult aphids tend to be about 1/16th inch in length, are soft bodied and pear shaped. Aphids have piercing-sucking mouthparts and have two protrusions on their rear tips called cornicles. Aphid adults can be winged (alate) or wingless (apterous). The formation of winged types is usually in response to overcrowding or poor host quality. The immatures or nymphs of the aphid are similar in appearance to the adult but smaller.

Origin and Distribution

Cotton aphid is nearly cosmopolitan, having a world-wide distribution. However, host specificity does vary depending on geographic origin.

Habitat & Hosts

Cotton aphids are extremely polyphagous and can feed on a large range of host plants covering 25 plant families. Among many others, notable hosts include asparagus, beans, begonia, catalpa, citrus, clover, cucurbits, cotton, eggplant, ground ivy, gardenia, hops, hibiscus, hydrangea, okra, peppers, potato, spinach, strawberries, tomatoes and violet. Crops typically most affected by cotton aphids include citrus, cotton and hibiscus.

Cotton aphids will initially be found feeding on the underside of new leaves, the plant terminal and flower buds, but as the population grows will infest the under side of older leaves.

Cotton aphids feed using sucking-piercing mouthparts which they use to pierce leaves and ingest copious amounts of plant sap from the phloem. Feeding robs the plant of energy that would otherwise be utilized for growth or fruit production. Heavy and prolonged infestations can cause leaves to curl downward, older leaves to turn yellow and shed, plant fruit may also shed or suffer reduction in size.

Cotton aphids excrete wastes in the form of a syrup-like substance called honeydew. Honeydew will accumulate on the leaves (and other plant structures) giving them a shiny, sticky appearance. A black sooty mold will often grow on the honeydew covering the leaf which may partially inhibit photosynthesis. More importantly, the honeydew may accumulate on the lint of open cotton bolls rendering the lint undesirable for milling.

Cotton aphid is also an important vectors of over 50 plant viruses including cucumber mosaic virus, watermelon mosaic virus 2, and zucchini yellow mosaic virus. These viruses are non-persistent viruses and may be transmitted from aphid to plant in a little as 15 seconds.

Cotton aphids are often attended by ants, which collect an feed upon their honeydew.

Life Cycle

With exception of northern latitudes, cotton aphids in the United States are all females, reproduce asexually (parthenogenically), giving birth to live young without mating. Aphids have a tremendous reproductive capacity and nymphs are born with developing embryos already present; essentially aphids are born pregnant. One female may produce as many as 80 offspring that mature within 8 to 10 days. Thus, it is possible for cotton aphids to have as many as 50 generations per year. These generations also occur as frequently as every 5 to 7 days under optimum conditions. In northern latitudes cotton aphid is capable of producing sexual forms and laying eggs on catalpa and rose of sharon for overwintering purposes.

Wingless adults overwinter in protected areas on catalpa, hibiscus, and a number of weed hosts. In the greenhouse, they can be active year-round. In spring winged females fly to suitable host plants and can disperse great distances via wind and weather fronts.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Predators such as lady beetles, lacewings and syrphid flies, along with parasitoids and aphid-killing fungi are often the most effective means of managing an cotton aphids. These beneficial organisms can effectively prevent aphids from reaching the damaging levels. Aphid tending ants will often protect aphids from predators. Soil and seed applied insecticides offer protection during early plant growth, but foliarly applied insecticides are often necessary on more mature plants. Standard and organically certified insecticides are available, but cotton aphid is notorious for developing resistance to commonly used insecticides so adequate control is not certain.

Related Publications

Citations

Blackman, R.L. and V. F. Eastop. 2000. Aphids on the worlds crops: an identification and information guide 2nd edition. Chichester, UK: John Wiley & Sons Ltd.

Kerns, D.L., J.A. Yates and B.A Baugh. 2015. Economic threshold for cotton aphid (Hemiptera: Aphididae) on Cotton in the Southwestern United States. J. Econ. Entomol.108: 1795-1803.

Suhas, V., D. Kerns, C. Allen, R. Bowling, M. Brewer and M. Parajulee. 2017. Managing cotton insects in Texas. ENTO-075, 38 pp. http://agrilifelearn.tamu.edu/Managing-Cotton-Insects-in-Texas-p/ento-075.htm.

Bugwood Images

Click Beetle / Wireworm


Most recently reviewed by: Janet Hurley & Pat Porter (2018)

Common Name(s): Click beetle, Wireworm

Description

Click beetles are elongated, parallel-sided and usually bear backward projections on the side corners of the shield behind the head (pronotum). They are somewhat flattened and range in size and color by species. Smaller species are about 1/4 inches long. Most species are brown to black in color, although some have reddish and yellowish colors and patterns. The eyed click beetle, Alaus oculatus (Linnaeus), reaches 1-½ inches in length and is beautifully marked with prominent oval eye spots on the pronotum and mottled gray wing covers. When placed on their backs, these beetles characteristically “click”, snapping their thoracic segments (prothorax and mesothorax) to cause their bodies to flip in the air to right themselves. Larvae, called “wireworms,” are usually hard-bodied, brownish, ½ to 2-½ inch long and cylindrical, with three pairs of tiny true legs behind the head and a flattened, and an ornamented shield-like segment on the tail end of the body.

The false click beetles (Eucnemidae) are similar to click beetles, and some species can even “click.” They are less common and usually occur in wood just beginning to decay. The Texas beetle, Brachypsectrida fulva LeConte (Coleoptera: Brachypsectridae) somewhat resembles a 3/16-inch long click beetle without the clicking mechanism. There is only one species in this family.

Habitat & Hosts

Larval stages (wireworms) damage seeds and seedlings of a wide variety of crops including alfalfa, beans, beets, clovers, corn, cotton, grasses, small grains (wheat, oats, etc.) many vegetable and bedding plants.  They also tunnel into potato and sweet potato tubers. Larvae of some species, such as the eyed click beetle, occur in dead trees and rotting stumps and logs.  Adults of Deilater have two light-producing spots on the thorax and one of the abdomen, somewhat similar to that of lightning bugs (Lampyridea).

In some years, adults are extremely numerous and enter homes and other structures in significant numbers. Adults do not damage plants.

Life Cycle

Biology varies by species. In general, adults and larvae overwinter in the ground, becoming active in the spring. Adult females dig burrows and lay eggs around the base of host plants. Eggs hatch within a few weeks and larvae develop through several molts over a period of time from several months to over 4 years. They pupate in the cells within the soil in late summer or fall, and emerge as adults a few weeks thereafter. Generations can greatly overlap.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Minimize wireworm infestations through clean cultivation and clean fallowing. Infestations are most severe in no-tillage or reduced-tillage situations, particularly following alfalfa, cover crops, or grain. Planting shallow and under warm conditions often allows cotton seeds to germinate quickly so plants can outgrow wireworm injury potential rapidly.

Larvae of some species damage seeds and underground parts of crop plants. Management in agricultural settings varies by crop, and growers should consult publications specific to the crop being grown. It is often the case that significant stand damage requires a replant of the crop.

Wireworm damage can be difficult to diagnose, in part because the larvae are highly mobile in the soil and may no longer be present. Look for chewed tissue on seeds and young plant parts below ground.

Wireworm damage to cotton seedlings. Photo credit: Patrick Porter.

Wireworm damage to cotton seedlings. Photo credit: Patrick Porter.

 

Time-lapse video showing wireworm larvae seeking shelter in soil. Video credit: Patrick Porter.

Related Publications

Insects in the City “Click beetles gone wild

Wireworms at cottonbugs.tamu.edu

Bugwood Images