The rose sawfly larvae had just emerged and were tiny. Along came this predacious larva of the green lacewing and began eating them. Rose sawflies are a European species, while the green lacewing is native to NA. Lacewings are sometimes sold in nurseries for control of insects like the rose sawfly, but especially aphids. However, the next day, I discovered that the poor lacewing larva had in turn been preyed upon by a spider.

To see what an adult lacewing looks like: http://www.pbase.com/laroseforest/image/113759585
They are so different from their larval stage, being delicate and ethereal looking, with big golden eyes.