I shared you can never have too much ironweed (Vernonia spp.). That is because, for me, ironweed comes with my favorite visitor... The Denticulate Long-Horned Bee (Melissodes denticulatus) a specialist bee on ironweed.
Melissodes denticulatus is a native long-horned bee (the male antenna are longer than other species of bee). It is a solitary ground-nesting bee in the family Apidae. They are easy to ID once you start spotting them. The pollen of ironweed is uniquely WHITE. And Melissodes carries buckets of it on a thick, fluffy region of their hind legs called the scopa designed for pollen transport. They are black with gray hairs and brilliant blue eyes.... isn't she beautiful? I get right in there with my camera to photograph these beauties, and they're not bothered, not aggressive, and have never stung me. As solitary bees they are working, single moms, out there collecting pollen for their offspring. They don't have queens and worker bees like social hive bees to do the work of building and provisioning nest cells. As with most native solitary bees, she is doing all the work herself and she doesn't have time for you!
Melissodes, as a genus, are generally are fall fliers. Melissodes denticulatus here flies July through early September, in synchrony with the ironweed bloom. She is considered a oligolectic bee, collecting pollen from only a few picky sources. Some specialists are one hit wonders, requiring only one host plant (monolectic) and if they go, so goes the bee. All will generally visit other nectar sources, but specific pollen is required to successfully rear their larva to maturity. While other asters may possibly be on the menu for M.denticulatus, it is truly ironweed that is supreme for these girls. On sunny days, ironweed can be swarming with them. There are other Melissodes species that specialize on other asters or groups of asters such as sunflowers and thistles. So while you are enjoying the brilliant purple flowers, take a peek to see if our denticulate long-horn bee is visiting your ironweed and... plant some more!
To learn more about specialist bees and their needed host plants, check out Jarrod Fowler's Pollen Specialist Bees of the Eastern US. This intense guide shares the phenological emergence of many species, and the host plants from which they were recorded collecting pollen.