John Obermeyer

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Corn earworm moth numbers have been relatively low this season until recently, as numbers have exploded in pheromone traps. These moths will lay their eggs on numerous crops, with late-market sweet corn being particularly vulnerable at this time. Tomato and pepper growers should also be aware of the potential for earworm (also called fruitworm) damage, especially if these crops are surrounded by cornfields that are drying down  and are no longer attractive for egg laying.  


Several caterpillars in the ear can be very similar in appearance and habits, so identification to species of some of the worms in ears can be tricky. Note that, in general, you cannot use overall body color or damage for identification. Some identification tips, though not foolproof, appear below for the corn earworm, western bean cutworm, fall armyworm and European corn borer. We suggest you inspect cornfields soon before the larvae leave the ear and pupate.   This article was previously published in the Purdue Extension Pest & Crop Newsletter.


Figure 2. Fall armyworm feeding on kernels.

Fall armyworms (Figure 1) are only able to survive the winter in extreme southern US, along the Gulf Coast and in Florida. Fall armyworms tend to migrate northward gradually, with each successive generation moving several hundred miles further north. They reach Indiana every year, but their populations are unpredictable in numbers and location. This week we have received reports of fall armyworm infestation in corn from southwest Indiana and northern Elkhart County, so they are throughout the state. However, infestations tend to be spotty, with individual fields or even portions of a field showing damage, with neighboring fields uninfested. Fall armyworms will feed on corn at all stages of development and will feed on all above ground plant parts (Figure 2 and 3). However, their late arrival in Indiana (July-August) means that we are mostly concerned about feeding on kernels in the ear. Because of the higher value of the crop, sweet corn,[Read More…]