Spotted Cucumber Beetle – Diabrotica undecimpunctata – also known as the Southern Corn Rootworm.
Day Lily – Hemerocallis.
Adults yellow to green with eleven black / dark spots on the elytra.
Spotted Cucumber Beetles, or Southern Corn Rootworm Beetles, are considered big-time pests of crops and other plants. I have not noticed them on any of my plants (including the vegetables in the garden) except for the day lilies. As you can see from the second photo, they do feed on them (he appears to be eating the pollen). But I have only seen a few of these guys and have not noticed any damage. Click here for information on a related species, the Northern Corn Rootworm. Both beetles are known as skeletonizing leaf beetles (along with flea beetles and a host of others), because they eat the fleshy parts of the leaf but leave the “veins” and other thicker parts of the leaf untouched, leaving the leaves looking like skeletons.
Day lilies, although well-adapted to Iowa weather, are not native to the New World. If I were planting my own garden I would probably not use them for that reason (although they are not detrimental to your yard, I prefer native species). But, they were planted before I bought the house and so I’ll keep them. Besides, they are prolific bloomers and probably provide me with 90% of the bugs I photograph (hiding out in the blooms).
Photos taken with the Canon Digital Rebel XT / 350D and a Sigma 70-300mm Lens on July 4, 2008, in Davenport, Iowa.