none Lymantria dispar; BIOCHEMISTRY-; Haemolymph & tissue composition; HAEMOLYMPH-; Biochemical composition; HYMENOPTERAN-PARASITES; Glyptapanteles liparidis; Host haemolymph & body composition relations; AUSTRIA-; Haemolymph & body composition, hymenopteran parasite relations Glyptapanteles liparidis; LEPIDOPTERAN-HOSTS; Lymantria dispar; Host haemolymph & body composition relations; AUSTRIA-; Lepidopteran host haemolymph & body composition relations The hemolymph and total body tissue composition (carbohydrates, lipids, proteins, and free amino acids) of gypsy moth larvae (Lymantria dispar, Lymantriidae: Lepidoptera) were analyzed and compared with the composition of larvae infected by their main parasitoid, Glyptapanteles liparidis (Braconidae: Hymenoptera). In the body tissue the concentrations of total lipids and total proteins decreased, whereas the glycogen concentration in the total body tissue was significantly elevated and exceeded the concentration of the nonparasitized larvae by a factor of approximately 3. Trehalose, glucose, and sorbitol were found in the hemolymph of both parasitized and nonparasitized larvae, but levels of all three carbohydrates were significantly reduced in parasitized individuals. The total lipid concentration was not altered due to parasitism. In the hemolymph the concentrations of total proteins nearly doubled in parasitized larvae, whereas the total free amino acid concentration was reduced ; however, the levels of some single amino acids were reduced and those of others were elevated in the parasitized larvae. The polypeptide profile of the host hemolymph provided one parasitism-specific polypeptide at approximately 80 kDa. The results demonstrate that parasitization of gypsy moths by G. liparidis leads to significant alterations in levels of nearly all substance classes within the host's hemolymph and tissue.