Common name: tomato fruitworm; corn earworm; cotton bollworm
Host plants: tomato, corn, cucumber, eggplant, pepper, potato, sweet potato, snap bean, lima bean, pea, lettuce, spinach, collards, artichoke, asparagus, cabbage, pumpkin, squash, watermelon, okra, cantaloupe, cowpeas
Adult size: medium-size moth; wingspan 1 – 1.3 in (25 – 35 mm)
Life cycle: as many as four generations per year in temperate regions; year round in tropics
Description & Life Cycle: Female moths lay eggs daily throughout their life span of seven to ten days. The minute eggs, about half the diameter of a pinhead are laid singly on both the upper and lower sides of the leaves on the host plant. They are spherical with a flat top and ribs running from top to bottom. Colour ranges from white, cream, yellow or light brown and they develop a band on the second day which darkens as time progresses towards hatching.
Emerging larva are white with a brown head. They initially begin feeding in a group but as they develop through their four to six instars, they become cannibalistic and kill each other until usually one, or maybe two, larvae remain feeding on the one fruit.
When the larvae are mature, they drop to the ground where they will bury themselves down two to four inches (5-10 cm) to pupate. The cylindrical pupa is fairly hard-shelled and a shiny brown colour.
During the growing season in temperate regions, the pupating stage lasts ten to fourteen days before the mature moth emerges. In areas where the winters are relatively mild, the larvae will bury themselves a little deeper to pupate over the winter. Adult moths will emerge when the spring temperatures warm up…usually by late April or early May. In regions where the winters are harsher, the pupae do not survive. But the pupae are capable of entering into facultative diapause, or a state where further development is temporarily stopped. They do this in response to adverse changes in the environment such as during a severe drought. By entering diapause during adverse changes in environmental conditions, their reproductive success rate increases substantially upon the delayed emergence.
Adult moths are a light buff or beige colour with maybe a tinge of olive green. Markings are quite indistinct but for suggestions of dark spots near the bottom edge. Wingspan is one to one and a third inches (25-35 mm). The moths are nocturnal and migrate seasonally. A strong wind can carry them approximately 250 miles (400 km), into regions where the winters are too cold for the pupae to overwinter.
Special Notes: Native to the Western Hemisphere, except in the coldest regions.
This is a major agricultural pest in the larval stage, doing significant damage to developing fruits which adversely impacts on expected harvest yields.
Best control is through integrated pest management techniques as this pest has become resistant to many pesticides. Trap crops and/or deep ploughing are effective controls.
There are over one hundred predator insect species that will feed on the eggs and larvae of this pest species.
Posted on August 4, 2015