Texas Cuckoo Bee
Although this insect looks like a wasp, it is actually a bee. The Texas cuckoo bee (Nomada texana) does not look or act like its relatives. While the majority of native bees, as well as the honey bee, are pretty fuzzy, and females can often be seen collecting pollen, the cuckoo bee is not hairy at all and never collects pollen. It does feed at flowers, but only to satiate its appetite for nectar. Pollen collecting is done for the grubs (baby bees) and that is why only females perform this chore. But the cuckoo bees do not create and provision nests for their young. Instead, they enter the nests of other bees and lay their eggs inside when the rightful owner is not around. Around 25% of our bee species are parasitic, but they are never very numerous for the obvious reason that they would overwhelm their host species.
Cuckoo bees are usually seen when they are feeding at flowers, but I've also seen them hanging around the nests of solitary native bees. They actually wait at the nest entrance while the host is busy inside the hole. As soon as the nest owner flies off, the cuckoo bee slips inside, presumably to quickly lay its eggs. They don't stay inside very long and soon reappear and fly off.