For a long time, ladybugs intimidated me. That’s because I knew there were lots of species, and I was hesitant to dive in and figure them out. In recent weeks, I’ve seen dark colored lady beetles (they are in fact beetles and not true bugs) in several places at Mount Pisgah. I’m still trying to identify some of them, but here’s what I know so far.
In North America, there are more than 500 species in the Coccinellidae beetle family of round-shelled “ladybug” beetles. Given it’s Thanksgiving week, imagine a holiday table with 500 chairs, and now imagine that’s just one chair for each species in the family! The majority of species have individuals that look like each other, and can be identified by their size and the pattern of colors on the pronotum, which is the Victorian ruff-like section behind the head.
The exception is the multicolored Asian lady beetle, Harmonia axyridis, aka in Europe, the Harlequin ladybird. As an adjective, harlequin means “in a variety of colors” and the variety of names also fits. These beetles were brought to the U.S. to combat aphids and other pest insects. In the 1980s they began to outcompete other lady beetle species and now sometimes themselves are pests.
Usually, you can distinguish an Asian lady beetle by two large oval white “eyespots” on the pronotum, with black marks between them that form a W or M shape. The body color can vary from orange to red, often with many black spots, but sometimes with few or no spots. To confuse things further, they also can be black with red or orange spots, and no W or M markings, but a white bracket-shaped mark on the pronotum. Harlequins are also tricky, jester types!
Because I’ve seen so many darker lady beetles lately I had these questions: Are beetles that mature in the fall darker, so they can absorb the sun when it shines? Does an individual beetle become darker as the hours of daylight decrease?
I did find a paper that concludes lady beetles can survive at very cold temperatures (they froze the poor insects to about 10° F to learn just how cold). Males and females tolerated cold to the same degree, and lighter and darker beetles also showed no difference. Researchers have also found a gene, and gave it a name, pannier, that regulates color. They found black spot size does change with the temperature when the insect is pupating.
This last black lady beetle remains a mystery to me. To date, BugGuide has slotted it into the Coccinellidae family, and there it sits until someone with more bug chops than me is able to i.d. it to the genus or species level. I’ll leave a link below, so you can check back and see where it ends up!
Stay curious!
See more of Karen’s work here.
Sources:
Link to the final black lady beetle Mt. Pisgah photo: https://bugguide.net/node/view/2062076. Accessed 11/19/21.
Research about H. axyridis cold tolerance: https://www.researchgate.net/publication/233513089_Cold_Hardiness_of_the_Multicolored_Asian_Lady_Beetle_Coleoptera_Coccinellidae. Accessed 11/19/21.
Researchers who found the gene that controls darkness on MALB: https://theconversation.com/in-red-and-black-the-genetics-of-ladybug-spots-104811. Accessed 11/19/21.
Evolution of color patterns in H. axyridis: https://onlinelibrary.wiley.com/doi/full/10.1111/dgd.12592. Accessed 11/19/21.
