Caterpillar Pests on Row Crops1
Lesser cornstalk borer ( Plate 1 ). The larvae range from about 1/4" to 3/4". Its body is marked by alternating aqua-blue and reddish-brown bands. Smaller larvae may have alternating bands of tan and red. The larvae wiggle violently if disturbed. They feed primarily by boring into the stem, taproot or underground parts of the plant.
A telltale sign of lesser cornstalk borer infestation is the presence of silken tubes about 3/4" to 1" long ( Plate 2 ). The fragile tubes are covered with sand particles and are attached at the point of entry of the stem under attack. The tubes can be found just below the soil surface to a depth of about 1". This pest feeds on peanuts, beans of all types (including cowpeas), corn, small grains, peaches, pine seedlings, wild grass and legume roots.
Diamondback moth ( Plate 3 ). The diamondback moth is gray, about 1/3" long, and has a row of three light-colored, diamond-shaped markings on its back. The wings are folded back when at rest and have an elevated tip at the rear.
Diamondback larva ( Plate 4 ). The diamondback larva is a small, greenish caterpillar that rarely exceeds 1/3" in length. The larvae eat many holes in the leaves of cabbage, collards and members of cole crops.
Diamondback pupa ( Plate 5 ). The diamondback pupa can be found within a white net-like sack about 3/8" long. The pupa is usually found attached to the underside of a leaf. Most adult moths emerge from their pupae within seven to 14 days.
Soybean looper ( Plate 6 ). The soybean looper is a green caterpillar that generally has thin white lines running along the sides of its body. It is about 1-1/2" long. The looper tapers down from the rear to the head. There are two pairs of fleshy legs near the back of the body and one pair at the rear. The caterpillar "loops" when it moves, hence the name. The cabbage and soybean looper are almost identical.
Corn earworm ( Plate 7 and Plate 8 ). The corn earworm is a serious pest, and is also known as the tomato fruitworm, cotton bollworm, soybean podworm and corn budworm. It is a robust caterpillar that generally reaches 1-1/2" in length when mature.
The corn earworm usually has a prominent yellowish or orangish head. The body is sprinkled with small, dark bumps, which may each give rise to a tiny hair. Although brown and green are the usual colors, pink, yellow and bronze specimens are also common.
Velvetbean caterpillar ( Plate 9 ). The velvetbean caterpillar is a common pest of soybeans, peanuts and other legume crops. The larvae are slender, about the same diameter from head to tail. They have five pairs of fleshy legs, with the rear pair often appearing spread while at rest. The caterpillar may reach 2" in length when mature, and both green and brownish-black phases occur. Velvetbean caterpillars wiggle actively when disturbed.
Hornworm ( Plate 10 ). Hornworms are green caterpillars with white diagonal markings on their sides. The tomato hornworm larva has eight L-shaped stripes, each hooking backward, while the tobacco hornworm has seven oblique stripes that do not turn backward. The tomato hornworm usually has a black "horn" at the rear while the tobacco hornworm has a red horn. The horn is prominent from the time the larva hatches from the egg. Hornworms reach a length of 3" to 4" in three to four weeks. They are voracious feeders on tomatoes, tobacco, eggplants, peppers and weeds of the nightshade family.
Footnotes
This document is SP91, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date May 1991. Reviewed May 2003. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.
F.A. Johnson, Professor; D.E. Short, Professor; J.L. Castner, Scientific Photographer; Department of Entomology and Nematology, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611. The term plates, where used in this document, refers to color photographs that can be displayed on screen from the FAIRS CD-ROM. These photographs are not included in the printed document.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal
Opportunity Institution authorized to provide research, educational
information and other services only to individuals and institutions
that function with non-discrimination with respect to race, creed,
color, religion, age, disability, sex, sexual orientation, marital
status, national origin, political opinions or affiliations.
For more information on obtaining other extension publications,
contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service,
University of Florida, IFAS, Florida A. & M. University Cooperative
Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
