[4] Listrodromus nycthemerus is a very small wasp which is predominantly black and yellow.

[2] Listrodromus nycthemerus has been recorded from Europe where records come from Ireland,[6] Great Britain,[7] Netherlands, France, Spain, Germany, southern Norway, southern Sweden, southern Finland, Croatia and Austria.

[1] Listrodromus nycthemerus is a parasitoid of the holly blue, and has no other known host.

The wasp lays an egg on a first instar caterpillar of the holly blue, inserting the egg into the caterpillar's body and the adult wasp emerges from the chrysalis, killing the chrysalis before its emergence.

[8] The wasp population takes 6 or 7 years to reach its peak and at its peak as many as 99% of the holly blue caterpillars will be host to a larval wasp, causing the host population to crash.