Corn Earworms

Posted by & filed under Director Blog, Horticulture News.

Have you ever purchased or grown corn-on-the-cob that had a large caterpillar at the top of the ear as you pulled back the husk in preparation for cooking?  This is a corn earworm and is the larval stage of the earworm moth which Corn - Zea mays 'Rainbow'lays eggs on developing corn silks during the night. When the egg hatches, the larva crawls down the silk and into the ear to begin eating.  You are not likely to find more than one earworm per ear of corn because the caterpillars are cannibalistic as well as connoisseurs of sweet corn.  Control for both the homeowner and commercial grower can be challenging as silks continue to grow over a period of time. This means that even if silks are treated with a pesticide, new silk will appear that hasn’t been protected. This often requires applications every 2 to 3 days for effective control in mid June to early July when peak flights of these moths usually appear.  The only good news is that the moths do not care for silks that have dried.  And, since they begin to dry after two weeks, control treatments are only required during the first two of the three week silking-to-harvest period.