Early spring wildflowers, like the Virginia Spring Beauty (Claytonia virginica), are an important source of food for a host of small bees and other insects. Many insects gather pollen from these flowers and in doing so help to pollinate the plants.
Some species of bees, though, lack scopa (the pollen-collecting hairs) and do not collect pollen to feed their offspring. The genus Nomada, according to Wikipedia, is the largest genus of kleptoparasitic bees sometimes referred to as “cuckoo bees.” Kleptoparasitic bees are so named because they enter the nests of a host and lay eggs there, stealing resources that the host has already collected.
It is a little hard to see the body of the bee in the photo below, but if you look closely you can see its striped abdomen, which is wasp-like in appearance. I was not sure of the type of bee, so I posted it to BugGuide, a useful resource for insect identification, and one of the experts there identified the bee as belonging to the genus Nomada.
© Michael Q. Powell. All rights reserved.
Mike Powell 
[…] Last year I posted an image of a Cuckoo Bee on the same kind of flower. That bee does not collect pollen. Instead it enters the nests of a host and lay eggs there, stealing resources that the host has already collected. From what I understand the cuckoo bee waits for the miner bee to leave its burrow and then lays its egg there. The offspring of the cuckoo bee eats the pollen in the burrow and then eats the larva of the miner bee. Yikes! […]