Genus Mordella tumbling flower beetle and native bee on sticky cinquefoil, tumbling flower beetle on pearly everlasting flower.
This week’s crawly is a petite pollinator (just under one-quarter of an inch) with a fun and accurate common name. Meet the tumbling flower beetle (Genus Mordella).
Beetles in general are underrated as pollinators. Tumbling flower beetles likely take more exception to this than most beetles because they were the forerunners of beetle/flower symbiosis.
Ancient ancestors of our backyard tumblers were some of the first insects to use flowers as food and shelter; clever little bugs!
Currently there are over 1500 species of tumbling flower beetles spread out over every continent except Antarctica. Of those 1500 species, 200 live in North America.
Knowing which species is which at a glance is quite difficult because all 200 types of tumblers look basically the same: small, oblong, pointy and black.
Fun fact: Another common name for tumbling flower beetles is “pintail beetles.”
There are a few more colorful species of tumblers; some are yellow or reddish and can have bands or stripes on their elytra. The pictured shiny black tumbling beetle’s are the most common type found in Oregon, but we do have some that have a brown band at the base of their head and two brown bands down the centerline where their wings meet.
Before we get to their cool lifecycle, let’s back up a bit to “what’s in a name?”
Why are they called “tumbling” flower beetles? While they can fly, often as not tumblers will tumble off their flowers when startled, then continue to tumble around on the ground to confuse a would-be predator.
They have thick, strong rear legs which they use to spring away from danger.
Fun fact: To ensure erratic movement, they will use only one rear leg to tumble; even they aren’t sure how and where they will land. Once on the ground they will keep using one leg or the other until the potential predator leaves or they right themselves into “flight position” and take wing.
Often as not tumbling flower beetles can be found in groups on the heads of flowers, so 10, 20 or more of them tumbling all around would definitely make it hard for a single predator to zero in on a meal.
Keeping with their “safety in numbers” way of life, tumbling flower beetles will hang out not only with their own species, but with other species of tumblers and with whatever other (non-predatory) pollinators are also on their chosen flowers.
The adult tumblers have a preference for posies because pollen is their food source and they pollinate as they go. While they visit a variety of flowers, they prefer umbelliferous flowers.
Umbe…what?
Your vocabulary word for the week is, “umbelliferous.” Umbelliferous flowers are generally in the Apiaceae AKA carrot family. The “umbel” comes from their lacy umbrella-shaped flower heads. Queen Anne’s lace is a classic example of these types of flowers.
Carrot flowers and other composite flowers with densely packed flower heads allow the tumbling flower beetles a nice broad surface to congregate on and tumble off of.
It isn’t only adult Genus Mordella tumblers who are beneficial; their kiddos have their own separate good-for-the-soils contribution. Tumbling flower beetle larvae in this genus grow up inside rotting wood, so they help break down the decaying wood into nutrients so more trees and flowers can grow.
So keep an eye out for these teeny tumblers May – July and give ‘em a nod for bringing benefits ten times their size.