During late August, large caterpillars were seen crawling out of soybean fields and across roads in Iowa. Because of the large size (approximately 2 inches in length) of this caterpillar, it was easy to assume that it was doing some damage to soybean. The caterpillar is called a white-lined sphinx and has a “horn” protruding from the rear of the body. Fortunately, it is not a pest of soybean but feeds solely on weeds. The larva transforms into a sphinx moth, which also is called a hawk moth or hummingbird moth. During late August and September, these moths commonly probe nectar from flowers in gardens.

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Caterpillar of the white-lined sphinx moth.