Something eating my leaves?

My cascade hops leaves are starting to get a hole in the center root of the leaf. It starts small and gets bigger until the leaf starts to die. I haven't found the culprit yet. Should I spray it with something? Last night I stole some wheel bugs off of a nearby tree. They hatched there this spring and I have been watching them. Anyway, They are carnavors so I put them on my hops thinking they would take care of anything that comes their way. We'll see!

Here are pictures of the leaves with holes and the new Hop Guardians.

Cascade with hole in leaves on Flickr - Photo Sharing!
Cascade whith hole in leaves on Flickr - Photo Sharing!
Wheel Bugs! on Flickr - Photo Sharing!

We spray all our herbs and veggies with a non-toxic pesticide, keeps the little buggers away. Still requires rinsing before use, but i'd rather rinse before use than have it eaten by an ungrateful bug before I get a chance to use it.