Meet the Beetles (in my flowers)

My native Spiraea plants bloom each June, each inflorescence of tiny white flowers becoming a showy beacon of pollen and nectar for the insects whose life cycle apparently coincides with that time. By and large, the insects which are most attracted to it are beetles. It’s as if these beetles know that this is the right time to emerge! With Pollinator Week starting tomorrow, I thought now is a good time to celebrate these little-known pollinators.

I have two species of meadowsweet, which is what our native Spiraea is often called: white meadowsweet (Spiraea alba) and Virginia meadowsweet (Spiraea virginiana). The Virginia one is blooming vigorously right now and its location by my front steps means that I see it multiple times a day. The flowers are tiny but numerous. The long-horned beetles show up almost immediately, first singly and then pairing up in joyous feast of food and sex.

What always surprises me is just how many species of long-horned beetles show up. Even ones that look very similar, once you really look at them, turn out to be not just a different species but even a different genus! Here are some of the ones that I’ve seen on these flowers.

Red-shoulder pine borer
(Stictoleptura canadensis) 

Flower long-horned beetle
(Strangalia luteicornis)

Margined leatherwing
(Chauliognathus marginatus)

Zebra long-horned beetle
(Typocerus zebra)

A less-showy visitor is a very small species of scarab beetles in the genus Trichiotinus. What they don’t have in looks, they make up for in numbers - these tiny guys are all over the flowers. Among all these beetles can be found the occasional small bees (sweat bees), large and noisy brown-belted bumble bees, and I even found a mosquito taking a rest on the flowers. 

Scarab beetle (Trichiotinus)

By the way, another similar shrub which also attracts these beetles is smooth hydrangea (Hydrangea arborescens). I have seen these same insects on those clusters of tiny flowers.

Back to the beetles – where do they come from? All the native beetles that I’ve mentioned are wood beetles: their mommas deposit eggs in soft wood and the larvae spend their youth chewing up and breaking down decaying and dead wood. In other words, they are cleaning up.