|Perilitus coccinellae cocoon, approx 6mm long|
|Adult P. coccinellae - note the wing venation and the needle-like ovipositor with the abdomen curled under the body|
|Adult P. coccinellae - a closer look at the ovipositor|
|Adult P. coccinellae - see how the abdomen is curled under the body|
The wasp has an interesting life history (as parasites often do). Although ladybird pupae are sometimes targeted, adults are usually parasitised. The wasp taps the ladybird with her antennae then curls the ovipositor forward and begins to tap and probe for weak points, laying a single egg into the ladybird along with trophic ('nutritional') cells which absorb food from the host so the wasp larva can feed on them once it hatches. It does not feed on the ladybird directly, although the diversion of nutrients to the parasite ipacts on the host's reproductive development and fat storage. After reaching its 4th instar, the larva chews its way out from the underside of the ladybird's abdomen, having immobilised it, possibly by affecting the host's motor neurones. It then forms the cocoon which is attached to the ladybird's legs. The ladybird is alive at this point which means that the wasp is protected by its warning colouration and reflex bleeding defence. The wasp then pupates, emerges as an adult and seeks a new host as soon as its wings are dry. The ladybird usually dies within about a week, either of starvation or fungal disease. Some host ladybirds do regain the use of their limbs although most are greatly weakened and die soon after. In winter the cycle stops for a while as the wasp larva hibernates within a host ladybird.
Majerus, M.E.N. (1994). Ladybirds. HarperCollins, London. [New Naturalist series]