A little ladybug

Brumoides septentrionis in Artemisia tridentata inflorescence

Last weekend, Kelly and I went for a hike in the South Hills on the Rimview trail. The hike started with a moose in the thick riparian growth along Rock Creek. It wasn’t long before we hiked out of the moose-infested riparian zone into shrub steppe. This is a fun trail because of the big views and it seems there is always something interesting. This time it was the ladybug, Brumoides septentrionis

The ladybugs most people think of are those aphid eaters in the subfamily Coccinellinae, but B. septentrionis is in the Chilocorinae, a group known to eat scale insects. The reason that people think of Coccinellinae when the topic turns to ladybugs is the Coccinellinae are larger, more colorful, and more common – usually.

We encountered about a 100 B. septentrionis during our hike. I collected some to send to a few friends. All of the insects we found were on Artemisia tridentata (sagebrush) in developing inflorescences. Quite a few insects feed on A. tridentata, so predatory insects aren’t too surprising. I never found any scale insects, much less got to watch B. septentrionis feeding, so I can’t be certain of why they where in the infloresence.

After getting home I started examining the collected and photographed B. septentrions and found them to be variable with regard to the extent of the black markings on the elytra. A couple were so dark that I initially thought they must be Exochomus, but that was silly.

Brumoides septentrionis later the same day on Pike Mountain

Once the observation of variability is made, then the questions begin to flow: what is normal? is there an advantage to being darker or lighter? are there dark and light individuals, or is there a wide range of possibilities? what factors maintain a diversity of markings? does coloration vary geographically? ad infinitum.

Which brings us to the moral of the story: observation. If not for looking at collected insects under the microscope and taking photos, I would not have noticed this in field. By using tools, we can extend the human senses. Sometimes our monkey brains find patterns in this extra sensory data, of course there are still exciting things to be found by simply looking.


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