sector Rs furcates into the veins Rs1 and Rs2, while in other Hymenoptera Rs1 is absent. The females bear a more or less long ovipositor, which in some species of Xyela may be as long as the body. Morphology of the ovipositor and the ovipositor sheath are important characters for identification to species level. The penis valves of the males are densely setulous, which is a rare character state among the basal lineages of Hymenoptera. Females and males mate with the bodies directing in opposite direction. In Xyelinae the genital capsule of the males are revolved for 180° after disclosure from the pupal skin (strophandry). Macroxyelinae are orthandrous after emergence. They mate in the same position as Xyelinae, but the male genital capsule is rotated yet in course of mating (facultative strophandry). Larva Like in many other sawflies, the larvae of Xyelidae are superficially similar to caterpillars of Lepidoptera ("eruciform" type of larvae). Larvae of species feeding inside plants are whitish, those of free-feeding species whitish green or yellow. Larvae of Megaxyela bear a conspicuous pattern of black spots (see plate 21 figure 3 in) or they resemble bird droppings. The roundish head capsule bears a larval eye (stemma) on each side, which is reduced in mining species, and short antennae comprising five articles. The thorax bears short legs comprising three articles. Unlike the larvae of all other Hymenoptera and Lepidoptera which lack prolegs on at least the first abdominal segment, larvae of Xyelidae have prolegs on all abdominal segments. In free feeding Xyelidae (Macroxyela, Megaxyela) the abdominal prolegs are conspicuous and consist of two articles, while in the mining species (Pleroneura, Xyela) they are reduced to inconspicuous transverse bulges. Pupa Unique among the Hymenoptera, the pupa of Xyelidae are of the decticous and exarate types, in which the antennae, legs and mandibles are free and mobile. This stage represents the already developed (pharate) imago which is still enclosed by the pupal skin. At this stage, the wings are not expanded, and in females, the ovipositor and its sheath curve dorsally above the tip of the abdomen. The decticous pupae are capable of biting open the cocoon, digging to the surface of the ground, moving around on the surface, and drinking (figs 22-23 in). This pupal form is an ancestral character of endopterygote insects. In other orders, it occurs in including Neuropterida, Mecoptera, Trichoptera and in the basal lineages of