Last week I spent some time examining flowering plants, looking for insect pollinators. I came across this flower fly (family Syrphidae) with its behind sticking out of the inflorescence of a cutleaf toothwort (Dentaria laciniata, Brassicaceae). It was probably enjoying the sugary nectar provided by the plant. At the same time, it was probably spreading pollen from plant to plant, helping to pollinate the flowers and aid plant reproduction.
While I was trying to photograph the fly, I realized I would have to move the flowers slightly to the side to get a clear shot. I was worried I would scare the fly off, so I was being very careful. After manipulating the flowers for a minute, I was somewhat surprised that the fly didn’t move. Then I suddenly realized why:
The fly was in the clutches of a flower crab spider (family Thomisidae). These spiders wait near flowers for pollinators to approach and then ambush them. After delivering potent paralyzing venom, they grab their prey and suck out the juices.
I’ve written about these crab spiders once before, but this was the first time I saw one with prey. The hairy body and rear-facing posterior lateral eyes suggest this spider is of the genus Mecaphesa.