none The biology of Perilitus sp. (unnamed new species) parasitizing H. abietis (L.) is briefly described. The Perilitus female has 2 ovaries which contain 30-210 eggs. Upon egg hatching in the host, the trophamnion breaks up into teratozoits, which swell during the parasitoid development. The larvae leave their host after apprx 17 days whereupon the host dies. Cocoons are spun in the ground, not far from the host remnants. Development time in the cocoon is apprx 10 days. The parasitoid has been observed parasitizing H. abietis from the beginning of May-Oct. The suitability of H. abietis adults as parasitoid hosts is briefly discussed.