Polygonia interrogationis on hops

Among the many pests we discovered in our hop yard this year was the Question Mark Butterfly (Polygonia interrogationis). As late instar larvae they managed to completely defoliate an entire plant!

Of course since we are entomologists we saved the larvae in the lab to rear them into adults. The larvae are dark with bright yellow spikes

Herbert A. 'Joe' Pase III, Bugwood.org

The pupae are brown except for silver spots which can vary in size, but there are usually eight of them. They attach themselves to leaves with silk and hang there until adults emerge

Herbert A. 'Joe' Pase III, Bugwood.org

On the adult, the upperside of the forewing is red-orange with black spots. The underside is light brown and a pearly white question mark in center is often located in the center of the hindwing.

If this pest becomes a serious problem applications of Bt will control them. Please read and follow any pesticide label carefully.