Leucospis is among the largest and most visually attractive of all chalcidoids. The genus was originally described by Fabricius in 1775. Leucospis affinis was described by Thomas Say, one of the first entomologists in North America, in 1824. These chalcids mimic wasps or bees with their bright coloration, ranging from black and yellow to orange. Leucospids are commonly mistaken for a yellow jackets and they are more common than you might think.
Leucospidae are parasitoids of a number of different species of solitary bees and wasps. While the family includes a wide variety of hosts, noticeable species include mason bees in the genus Osmia, leafcutter bees, and orchid bees (Eulaema meriana). Leucospids have a distinct, long ovipositor that is wrapped around the top of its abdomen and stored inside an ovipositor sheath. The females will use their antennae to locate a larva of their host species within its nest. Mother Leucospid will then unsheath her long ovipositor and drill into the wood or dry mud wall of the host’s nest to lay her egg inside the cell. The egg will hatch and the larvae will search the cell in the nest for competing parasitoids. It will be the only parasitoid larva to survive in the cell. It will then spend the rest of its larval days as an ectoparasitoid, sucking the body fluids of the host larva until it is ready to pupate into an adult. Unlike the larva, the adults are nectar feeders. They lick the nectar from shallow to medium-depth flower blossoms. Keep an eye out for leucospids the next time you are out watering your flowers!