Nomada bees: the home invasion specialists
About twenty percent of all bee species in North America don’t bother to collect pollen. It’s not that they don’t need pollen for raising their young, because they do. But they would rather steal it than do all that hard work.
We always think of bees as being the ultimate pollinators, so that one-in-five number is sobering. These so-called cuckoo bees don’t even have the hairy bodies we usually associate with bees. In fact, they look like more like wasps.
So how do they manage to raise their families? Easy. They just hang around a nest that is under construction. When the female bee—often an Andrena—goes out for another load of pollen, the cuckoo bee darts in, lays an egg on the pollen provision, and “gets the hell out of Dodge.” That’s it: motherhood is convenient, quick, and clean. No mess, no fuss, no toiling all day over a hot flower.
Last week I took a short stroll to my favorite springtime bee place in the Mima Mounds Natural Area, a big patch of kinnikinnick in the middle of the prairie. Within ten minutes I spotted at least 8 types of bee: two bumble species, two Andrena species, one species of Habropoda, one Halictus, two Nomada species, and two other species I couldn’t identify. It’s the Nomada that are the cuckoo bees (also known as cleptoparasites).
Nomada isn’t the only genus of cuckoos, but it is one of the largest. Once the egg hatches, the Nomada larva destroys the egg or larva left by the host bee and then uses the pollen provision to grow on. The different species of cuckoo bees vary in their selection of hosts and their growth pattern, but they all invade the nests of other bees.
The Nomada shown is probably parasitic on the Andrena seen in the last two photos. I can’t be absolutely certain because I never found any nests, but the fact they are active at the same time and place is a good clue.