A Monarch Enemy
Chuck Patterson saw this innocent-looking fly in his milkweed patch in Driftwood, TX, but he recognized it as a dangerous monarch enemy:

"Unfortunately we have witnessed one of the monarch's most damaging parasitoids. The tachinid fly (Lespesia archippivora) has infected numerous larvae around our house and kept them from achieving pupation. We isolate the fly pupae when it's discovered and prevent them from returning to the milkweed patch."