Fine structure of adhesive devices of Strepsiptera (Insecta)

Legs and other body parts of males, females and first instar larvae of almost all recognised families of Strepsiptera (Insecta) were examined. Descriptions of tibial, tarsal and pretarsal adhesive structures for each family are presented. These and attachment devices not associated with the legs are discussed. Strepsiptera evolved two strictly different types of tarsal attachment structures: hairy surfaces in the males and smooth flexible pads in the first instar larvae. Additional adhesive devices are present in several subgroups: mushroom-shaped microtrichia on the maxillary palp of males of Bohartillidae and acute pointed tibiae, or tarsal segments of males in different families. First instar larvae have evolved adhesive hairs on the ventral side of the body and on the podomeres. Specialised adhesive hairs are absent in the groundplan of adult males of Strepsiptera, but have evolved with the adoption of permanent endoparasitism of females. The most elaborate attachment structures, both in males and first instar larvae, are present in parasites of fast flying hymenopteran hosts (Aculeata).