Egg mass structure of the processionary caterpillar Ochrogaster lunifer (Lepidoptera: Notodontidae): is the outer egg layer sacrificed for attack by the egg parasitoid Anastatus fuligispina (Hymenoptera: Chalcidoidea: Eupelmidae)?

Each life stage of an insect faces the challenge of various mortality factors. Through experimental and observa-tional studies, we use those mortality agents to our advantage to control outbreaks of pest insects. Theprocessionary caterpillarOchrogaster luniferHerrich-Schäffer, 1855, is a widespread native moth in Australia thatdefoliates host trees and causes medical problems in humans and animals.Anastatus fuligispina(Girault 1939) isan egg parasitoid described from eggs ofO. luniferin eastern Australia nearly 80 years ago for which few life his-tory traits are known. This is thefirst study to investigate the life history ofA. fuligispina, factors associated withparasitism levels inO. luniferegg masses and its impacts on egg mortality. We found that parasitism level wasrelated to the total number of eggs in anO. luniferegg mass, with higher parasitism occurring in masses with fewereggs. The inaccessible physical structure of theO. luniferegg mass by layering and encasing eggs with other eggsand the searching efficiency of the parasitoid are possible key factors. Other variables such as exposure time in thefield, host tree species and number of undeveloped eggs in the egg mass did not affect the level of parasitism. Fur-ther investigations on the life history ofA. fuligispinamay open possibilities for its application in controllingO. luniferpopulations.