Battle of the Bugs: Tomato Fruitworms/Corn Earworms




Most gardeners have experienced damage caused by this destructive insect.  In fact, it is one of the most costly pests in the United States as it attacks many important field and vegetable crops.  Corn, tomatoes, pepper, cotton, sorghum, beans, and lettuce are seriously damaged, but Heliocoverpa zea also attacks other fruits, flowers, and weeds.  This single insect pest is called by many common names, but the most popular are the tomato fruitworm, the corn earworm, sorghum headworm, and the cotton bollworm.  


Close to 3000 eggs are laid by the female moth close to a full moon.  Target sites are on the silk of corn or on new leaves near fruit of tomatoes and peppers.  The corn earworms develop for about 4 weeks, becoming cannibalistic on others worms in the same ear of corn.  Then they drop to soil to pupate for a couple of weeks and emerge as adults.  Adults mate then live two weeks to distribute eggs. The moths have been found at 10,000 feet as they disperse up into Canada to Mexico. Three generations are produced per year with the overwintering limit occurring around Interstate 70. 


Natural control of the tomato fruitworm is by parasitism with tachinid flies, trichogamma wasps, and naturally occurring Bacillus thuringiensis (Bt). 


For organic control, a drop or two of mineral oil on the corn silk right after pollination will trap the young caterpillar before it reaches the ear.  Other strategies are to dust with diatomaceous earth, spray with Bt in the evenings, introduce parasitic wasps (Campoletis sonorensis and C. nigriceps), plant resistant corn hybrids, and apply beneficial nematodes to the soil and to simply plant corn early.  Some cotton farmers have had success with evening garlic sprays to control this and many other insect pests.


For specific chemical control recommendations, go to the LSU AgCenter website.


1 Response so far »

  1. 1

    […] Battle of the Bugs: Tomato Fruitworms/Corn Earworms […]

Comment RSS · TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: