Green caterpillar
Hyles lineata caterpillar. The moth is known as the white-lined sphinx in the family Sphingidae. With a wide geographic range throughout Central and North America, H. lineata is known to feed on many different host plants as caterpillars and pollinate a variety of flowers as adults. Caterpillars are powerful eaters and are known to form massive groupings capable of damaging crops and gardens. An orange horn protruding from the back of the body is a distinguishing characteristic of Hyles lineata caterpillars. This horn, which may sometimes be yellow and have a black tip, is not a stinger. (Wikipedia)
In the TWU Butterfly Garden it probably fed on Evening Primrose since this species was the only one we have from the list of preferred species by H. lineata.
Green caterpillar
Hyles lineata caterpillar. The moth is known as the white-lined sphinx in the family Sphingidae. With a wide geographic range throughout Central and North America, H. lineata is known to feed on many different host plants as caterpillars and pollinate a variety of flowers as adults. Caterpillars are powerful eaters and are known to form massive groupings capable of damaging crops and gardens. An orange horn protruding from the back of the body is a distinguishing characteristic of Hyles lineata caterpillars. This horn, which may sometimes be yellow and have a black tip, is not a stinger. (Wikipedia)
In the TWU Butterfly Garden it probably fed on Evening Primrose since this species was the only one we have from the list of preferred species by H. lineata.