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Extension Entomology

Lesser Cornstalk Borer

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Article author: Kate Crumley
Most recently reviewed by: Tyler Mays & Danielle Sekula (2021)

Common Name(s): Lesser Cornstalk Borer

Description

The lesser cornstalk borer is a small, yellow to black moth with sexual dimorphism that varies by location. This moth species is a pest on a variety of grain and legume crops, with larvae that feed by tunneling into the stem of the host plant.

Origin and Distribution

The lesser cornstalk borer is native to the United States. It can be found from Maine to California, and has been documented in Hawaii, but is most often found in sandy soils in the southeastern United States. It can also be found in Mexico, Central, and South America.

Habitat & Hosts

The lesser cornstalk borer is a polyphagous pest that feeds on a variety of crops. Vegetable and legume crops are often damaged, and it has a variety of weedy hosts like crabgrass, johnsongrass, wild oats, bermudagrass, wiregrass, goosegrass, and nutsedge.

Life Cycle

Lesser cornstalk borer eggs are oval, and are 0.35mm – 0.43 mm in width, and green when first laid, but turn pink after 8- 24 hours. Eggs turn deeper red as they near hatching, and are a deep iridescent crimson immediately before. Eggs take between 2- 3.5 days to hatch depending on temperature. Larvae that can be found in silk tunnels radiating horizontally from the stems of their host plants immediately below the soil surface. The silk tubes are usually between two or three inches long, depending on the age of the larvae. Larvae normally have 6 instars, but can range from 5- 9, and range from 1.3 mm to 20.8 mm long. The larval stage lasts about 20 days when not overwintering. Pupae can be found in the silk tunnels near base of the plant, or loose in the soil. They are yellow early, and turn dark brown to nearly black before adults eclose. They range from 7.6 mm to 9.6 mm in length. The pupal stage can last from 7- 10 days when not overwintering. Adult moths are 8-9 mm long brown moths with sexual dimorphism, and color patterns that vary based on location. Adults live for about 10 days, and are most active at night.

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.

Damage from the lesser cornstalk borer is caused by feeding, which tunnels into the stem of the plant or girdles the base of the plant. Wilting is one of the early symptoms of infestation, and can result in a poor crop stand. Insecticides can be used to control this pest, but need to be applied to the root zone, either in the seed furrow or banded over the seed bed. Modified planting practices can be used to minimize damage. Insect populations increase later in the growing season, so early planting can help. Tillage and weed control also help minimize insect populations in the environment, but conservation tillage can also help. Conservation tillage can allow larvae to feed freely on crop residue and organic matter, which can spare seedlings.

Related Publications

http://entnemdept.ufl.edu/creatures/field/lesser_cornstalk_borer.htm#damage

https://entomology.ca.uky.edu/ef129

Citations

All JN, Gallaher RN, Jellum MD. 1979. Influence of planting date, preplanting weed control, irrigation, and conservation tillage practices on efficacy of planting time insecticide applications for control of lesser cornstalk borer in field corn. Journal of Economic Entomology 72: 265-268.

Bessin R. 2004. The common stalk borer in corn. University of Kentucky, Entomology. University of Kentucky, Lexington, KY. http://www.ca.uky.edu/entomology/entfacts/ef100.asp (5 September 2008)

Biddle AJ, Hutchins SH, Wightman JA. 1992. Pests living below ground, Elasmopalpus lignosellus: Lesser cornstalk borer, pp. 202-203. In McKinley RG. [editor] Vegetable Crop Pests. CRC press, Boca Raton, FL.

Capinera JL. 2001. Handbook of Vegetable Pests. Academic Press, San Diego. 729 pp.

Chang V, Ota AK. 1987. The lesser cornstalk borer: a new important pest of young sugarcane, pp. 27-30 In Annual Report, 1986. Experiment station. Hawaiian Sugar Planter’s Association, Pahala, HI.

Chapin JW. (1999). Lesser cornstalk borer on peanut. Entomology insect information Series. http://entweb.clemson.edu/eiis/pdfs/ag21.pdf (20 August 2008).

Funderburk JE, Boucias DG, Herzog DC, Sprenkel RK, Lynch RE. 1984. Parasitoids and pathogens of larval lesser cornstalk borers (Lepidoptera: Pyralidae) in northern Florida. Environmental Entomology 13: 1319-1323.

Funderburk JE, Herzog DC, Mack TP, Lynch RE. 1985. Sampling lesser cornstalk borer (Lepidoptera: Pyralidae) adults in several crops with reference to adult dispersion patterns. Environmental Entomology 14: 452-458.

Gardner WA, All JN. 1982. Chemical control of the lesser cornstalk borer in grain sorghum. Journal of Georgia Entomological Society. 17: 167-171.

Isely D. 1944. The lesser cornstalk borer, a pest of fall beans. Journal of Kansas Entomological Society. 17: 51-57.

Leuck DB. 1966. Biology of the lesser cornstalk borer in south Georgia. Journal of Economic Entomology 59: 797-801.

Luginbill P, Ainslie GG. 1917. The lesser cornstalk borer. U.S. Department of Agriculture Bulletin 539. 27 pp.

Lynch RE, Klun JA, Leonhardt BA, Schwarz M, Garner JW. 1984. Female sex pheromone of the lesser cornstalk borer, Elasmopalpus lignosellus (Lepidoptera: Pyralidae). Environmental Entomology 13: 121-126.

Mack TP, Backman CB. 1984. Effects of temperature and adult age on the oviposition rate of Elasmopalpus lignosellus (Zeller), the lesser cornstalk borer. Environmental Entomology. 13: 966-969.

Mack TP, Davis DP, Backman CB. 1991. Predicting lesser cornstalk borer (Lepidoptera: Pyralidae) larval density from estimates of adult abundance in peanut fields. Journal of Entomological Science 26: 223-230.

Mack TP, Davis DP, Lynch RE. 1993. Development of a system to time scouting for the lesser cornstalk borer (Lepidoptera: Pyralidae) attacking peanuts in the southeastern United States. Journal of Economic Entomology 86: 164-173.

Metcalf CL, Flint WP, Metalf RL. 1962. Lesser cornstalk borer, pp. 497-498. In Destructive and useful insects. McGraw-Hill Book Company, San Francisco, CA.

Nuessly GS, Webb SE. (2007). Insect management for sweet corn. EDIS. http://edis.ifas.ufl.edu/IG158 (7 May 2020).

Riley CV. 1882. The smaller corn stalk-borer. U. S. Department of Agriculture Report 1881: 142-145.

Sanchez, Louis O. 1960. The biology and control of the lesser cornstalk borer, Elasmopalpus lignosellus.

Schaaf AC. 1974. Jumping borer, Elasmopalpus lignosellus, pp. 31-34. In Handbook of pests of sugarcane. Tech Bull 1/75. Sugar Industry Research Institute Mandeville, Jamaica.

Smith JW Jr, Barfield CS. 1982. Management of preharvest insects, pp. 250- 325. In Pattee HE, Young CT (editors), Peanut science and technology. American Peanut Research Education Society, Yoakum, TX.

Smith Jr JW, Johnson SJ, Sams RL. 1981. Spatial distribution of lesser cornstalk borer eggs in peanuts. Environmental Entomology 10: 192-193.

Smith Jr JW, Johnson SJ. 1989. Natural mortality of the lesser cornstalk borer (Lepidoptera: Pyralidae) in a peanut agroecosystem. Environmental Entomology 18: 69-77.).

Tippins HH. 1982. A Review of Information on the Lesser Cornstalk Borer Elasmopalpus lignosellus (Zeller). Georgia Agricultural Experiment Station Special Publication 17. 65 pp.

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Soybean Podworm

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Article author: David Kerns, Pat Porter
Most recently reviewed by: (1970)

Common Name(s): Corn earworm, Cotton Bollworm, Sorghum headworm, Soybean Podworm, Tomato Fruitworm

Description

The soybean podworm is also known as the corn earworm, cotton bollworm, sorghum headworm and tomato fruitworm and can be found on many garden and farm crops and non-crop vegetation. In most soybean production, soybean podworm is referred to as corn earworm. Adults have buff-colored wings and rather stout bodies. The wingspan is approximately 1½ inches. They are good fliers and can easily move from field to field and often arrive in large numbers on storm fronts. The moths only feed on nectar and are not pests.

However, each female can lay 500 or more eggs. The eggs are laid singly and, when new, are pearly white. The color changes to a yellow/dull white tint over time before hatching. Small caterpillars look much like the small caterpillars of other species, and it is difficult to identify them without a microscope. Soybean podworm caterpillars have many microspines on the back and sides of the body, and these are not found on most other common caterpillar pests. Larvae have a tan head and alternating dark and light stripes running lengthwise down the body, and they have numerous tubercles (dark spots) with long spines. Other pest species have stripes as well, but they do not have the abundance of microspines and tubercles, and a 10x hand lens will allow differentiation. There is no “typical” larval color, and it is common to find larvae that are either light green, dark green to grey green, or pink. Full grown larvae are approximately 1.5 inches long.

A very similar pest that may be found infesting soybean is the tobacco budworm. Eggs and larvae of soybean podworm and tobacco budworm indistinguishable without fine magnification. Tobacco budworm larvae have a tooth-like projection, called a retinaculum, on the inside surface of the mandibles and fine short hairs on the first, second and eighth abdominal projection (tubercle) which bear a single, prominent spine. If the projection and hairs are absent, this indicates a podworm. Damage and management of these two pests are the same in soybean. Soybean podworm may be distinguished from other soybean infesting caterpillars primarily based on the number of pairs of abdominal prolegs.

 

Origin and Distribution

The soybean podworm is a New World insect (Western Hemisphere) and is present throughout this region. It overwinters only in areas with mild winters, but flies to other areas during the course of the spring, summer and fall.

Habitat & Hosts

Soybean podworm has a very wide host range, and in Texas is usually the caterpillar found in ears of corn. Other cultivated hosts include tomato, sorghum, cotton, sunflower, squash, watermelon, potato, sweet potato, asparagus, artichoke, cowpea, snap pea, green bean, cabbage, cantaloupe, collard, cucumber eggplant, pepper, watermelon and others. The first generation of soybean podworm primarily develops on wild hosts, principally clovers. The second generation develops primarily on corn. Among soybean podworm hosts, corn is the most suitable of all hosts. The third and fourth generations generally occur in other agronomic host crops such as soybean, cotton, and grain sorghum with the fifth generation occurring primarily on volunteer crop plants after harvest and on other non-crop wild hosts.

Host preference of soybean podworm is positively correlated to plant maturity and it strongly prefers plants in the flowering stage. Thus, egg lay in soybean most often occurs during flowering or the R1-R2 stages. Later infestations may occur but are much less common. High infestations of soybean podworm often follow pyrethroid applications during bloom, due to destruction of natural enemies.

Although a less common pest of soybean in Texas, in other parts of the southern U.S. soybean podworm is often the most economically important insect pest of soybean. Soybean podworm causes damage to soybean through defoliation and from consuming pods. Early instars typically feed on blooms and and leaves. Feeding on blooms is not considered economical and defoliation by podworms alone is usually not severe enough to warrant control. Most damage is associated with 3rd-6th instar larvae which will feed upon leaves, but more importantly soybean pods. One larva can consume 15-20 flat pods or 6-10 older pods.

 

Life Cycle

Adults are quite mobile and can lay eggs on any host that is at a susceptible stage. Eggs are often laid near or on fruiting structures, but they can be laid on leaves and stems as well. Eggs hatch in 3-5 days and there will be five to six larval instars, each separated by a molt to a larger caterpillar. The larval stage lasts from 13 to 31 days depending on temperature. Insects develop faster under higher temperatures. After the last larval stage, the larvae move to the soil and construct a burrow where they will remain while in the pupal stage, which lasts from 10 – 25 days depending on temperature. Adults then emerge and will live for an average of 10 days, some more and some less. Soybean podworm overwinters in south Texas, and often flies north carried on storm fronts. There are several generations per year and the insect can be expected to be present for most of the growing season in the south, but only increases gradually in number in northern parts of the state. However, the growing season starts later in the north, and soybean podworm is usually quite abundant by the time vegetables and other crops reach susceptible stages.

Soybean podworm larvae are cannibalistic but in soybean they are usually not confined to groups in small areas so this behavior is inconsequential.

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.

Most states have well defined action threshold to aid in management decision making. Sampling for soybean podworm usually involves sweep net or drop cloth. In much of the southern U.S., pyrethroid resistance is common in soybean podworm populations so caution should be used if using a pyrethroid for podworm control. Commonly used insecticides for soybean podworm and tobacco budworm include products containing chlorantraniliprole, spinetoram or spinosad. Additionally, the nucleaopolyhedrovirus, i.e. Heligen, has proven to be an effective alternative to chemical insecticides.

Related Publications

Citations

Adams, B.P., D.R. Cook, A.L. Catchot, J. Gore, F. Musser, S.D. Stewart, D. L. Kerns, G. M. Lorenz, J.T. Irby and B. Golden. 2016. Evaluation of corn earworm, Helicoverpa zea, (Lepidoptera: Noctuidae), economic injury levels in Mid-South reporductive stage soybean. J. Econ. Entomol. 109: 1161–1166.

Flanders, K. and R. Smith. 2008. Identifying caterpillars in field, forage, and horticultural crops. Alabama Cooperative Extension, ANR-1121. http://www.aces.edu/pubs/docs/A/ANR-1121/ANR-1121.pdf.

Hartstack, A. W., J. P. Hollingsworth, R. L. Ridgway, and J. R. Coppedge. 1973. A population dynamics study of the bollworm and the tobacco budworm with light traps. Environ. Entomol. 2: 244–252.

Mueller, A. J., and B. W. Engroff. 1980. Effects of infestation levels of Heliothis zea on soybean. J. Econ. Entomol. 73: 271–275.

Smith, R. H., and M. H. Bass. 1972. Soybean response to various levels of podworm damage. J. Econ. Entomol. 65: 193–195.

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Cotton aphid/Melon aphid

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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.

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