Cuckoo wasps are also called gold wasps. They are usually small, metallic, and heavily armored, the latter for a very good reason. The wasps are parasites in the nests of other wasps or bees. The female slips into the nest of the host, laying an egg inside. After the egg hatches, the cuckoo wasp’s larva eats either the rightful inhabitant or in many cases the food stored in the nest.
These wasps have no stinger, so when they are attacked they curl into a ball for defense which is very effective given their string armor.
The species name borealis is a Latin word derived from the Greek word boreas which means north and refers to the known species distribution in the Nordic and Baltic countries and north-western Russia.
For the experts: The Chrysididae are a group of cleptoparasitic and parasitoid aculeate wasps with a large number of rare and endangered species. The taxonomy of this group has long been confusing due to the similarity of species and extensive intraspecific variation. We present for the first time a comprehensive dichotomous key for all 74 species found in the Nordic and Baltic countries. In addition to diagnostic characters, information on the distribution and biology of each species is also presented. A new species, Chrysis borealis Paukkunen, Ødegaard & Soon, sp. n. is described on the basis of specimens collected from Fennoscandia. Chrysis gracillima Förster, 1853 is recorded as new to the Nordic and Baltic countries.