Oval Beach, Saugatuck, Allegan County, Michigan, USA September 22, 2014
I know what they are (mostly) but can anyone identify the reason why this Lake Michigan beach is currently hosting several thousand beetles? They are about 30 feet up from the water's edge, on driftwood and broken grasses left behind by stormy rough weather this weekend. I gathered a few clusters to make an informal count, and came up with about 90% Harmonia axyridis, with significant (6%) quantities of Diabrotica undecimpunctata, and several other lady beetle species too, including Hippodamia convergens, Hippodamia parenthesis, Coccinella septempunctata and Cycloneda munda. What brings this range of genera and species together in such quantity in this location? Preparing to hibernate? Migrate?
Contributed by Hannah Nendick-Mason on 23 September, 2014 - 9:12am Last updated 31 May, 2015 - 7:36am
Disclaimer: Dedicated naturalists volunteer their time and resources here to provide this service. We strive to provide accurate information, but we are mostly just amateurs attempting to make sense of a diverse natural world. If you need expert professional advice, contact your local extension office.