Explanation of Names
The name "cuckoo wasp" refers to the fact that these wasps lay eggs in the nests of unsuspecting hosts.
In our area, 3 subfamilies with 227 spp. in ~30 genera (most diverse in the west, with 166 spp. in CA alone(2)
). Worldwide, 5 subfamilies with >3000 described (~4,000 estimated) spp. in >80 genera(3)(4)
Overview of our fauna* –taxa not yet in the guide; classification adapted from(2)(4)
Characteristics of Chrysididae(5)(6)(4)
Body metallic blue or green, usually with coarse sculpturing (many pits in surface)
Antennae with 12 segments (females) or 13 segments (males), two to six (usually three) of them visible and concave or hollowed out beneaath
Rear corners of thorax pointed
Tip of abdomen in many species has tooth-like projections
Hindwings with no closed cells
Abdomen concave beneath, allowing chrysidids to curl up into a ball when disturbed (see below)
The wasp rolls up in a defensive position when disturbed
Throughout NA (most diverse in the west) and in all the zoogeographic regions worldwide
, except Antarctica; 10% of all our spp. are CA endemics(3)(4)(2)
Most species are external parasites of wasp and bee larvae; one subfamily (Cleptinae, one genus, Cleptes
) attacks sawfly
larvae, another subfamily (Amiseginae) the eggs of walkingsticks
Some species are parasitoids and others cleptoparasites. Either way the host larva dies.
Parasitoids feed on the larva of the host and cleptoparasites "steal" the host's food. The food-stealing behavior of cleptoparasite species resembles that of the cuckoo bird and gave rise to the cuckoo wasp's name. Hosts of parasitoid species include bees, sphecid wasps, potter wasps, sawflies, silk moths, and the eggs of stick insects. Cleptoparasitic species feed on provisions of sphecid wasp nests, which may include dead spiders, true bugs, aphids, or thrips.
The female sting has been modified into an egg-laying tube with highly reduced valvulae and poison gland. As a result, unlike most other aculeates, chrysidids cannot sting and can be easily handled.(2)
Some metallic-green sweat bees
(Halictidae) are superficially similar but lack the sculptured cuticle and the ability to curl up in a protective ball