Larra bicolor Fabricius

(Insecta: Hymenoptera: Crabronidae)

Larra bicolor is a solitary wasp that parasitizes mole crickets in the genus Scapteriscus, of which the following three species are pests in Florida: shortwinged mole cricket (Scapteriscus abbreviatus Scudder), southern mole cricket (Scapteriscus borellii Giglio-Tos), and tawny mole cricket (Scapteriscus vicinus Scudder).

The adult wasps are black with a red abdomen and smoky brown wings. Females are up to 22 mm long, and males are smaller.

In pursuit of a host, a female wasp enters a mole cricket gallery, chases the cricket into the open, and eventually stings and temporarily paralyzes it. She then deposits an egg on the soft, ventral side of the cricket between the first and seconds pairs of legs. Larvae hatch and live as ectoparasites attached by their mandibles to the host. Depending on temperature, larval development involving five instars may take between 12 and 30 days. The pupal stage lasts 50 days or longer if it overwinters. The adult wasps feed on nectar of flowers.

Native to South America, Larra bicolor was introduced several times into Florida in biocontrol programs targeting Scapteriscus mole crickets. The first attempt in 1940 was unsuccessful because of cold winter temperatures and led to 30 years of reliance on chemical control. Beginning in 1979, new introductions were made in North and South Florida, and by 2008, populations had established in at least 44 counties.

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