Aprosthema species are usually rarely found. In recent years, in southern France, relatively strong populations of A. tardum were detected, which allowed observations on the behaviour and development of the species to be made. The host plant in the study area is Lathyrus latifolius (Leguminosae). As in a few other Aprosthema species, whose development has been previously investigated in northern Europe, A. tardum is bivoltine, although a partial third generation may occur in southern Europe under favourable weather conditions. Adults display seasonal dimorphism, similar to that already described for A. melanurum. Individuals which overwinter make stronger cocoons in the soil (winter cocoons), whereas the more loosely spun cocoons (summer cocoons) of individuals which complete their whole development in a single season are usually found on aerial parts of the host, or plants of other species growing near to the host. The head behind the eyes is more strongly developed in adults which emerge from winter cocoons. A few individuals of A. tardum in the first generation, which normally form summer cocoons, make winter cocoons and enter prolonged diapause, like almost all larvae of the second generation. During oviposition the valvulae 3 are deployed so that their inner surfaces are in very close contact with the leaf epidermis. We suggest that this behaviour is connected to the presence of spines on the valvula inner surface. The latter are found in many argid sawflies, but not in other families of Palaearctic Tenthredinoidea, in which the valvulae have not been observed to be used in a similar way.

Unusually for Ichneumonidae, Trogus lapidator emerges through a hole in the pupal wing case of its papilionid butterfly host that is made largely by a liquid secretion that softens and disintegrates the host tissue. The mandibles are deployed to help spread the secretion, but only towards the very end of the emergence process are they used (and then only in a minor way) to enlarge the hole. Links to video clips showing the emergence of T. lapidator are provided. Photographs illustrating the nature of emergence holes left in Lepidoptera pupae by a range of Ichneumonidae and some Chalcidoidea are presented and discussed, contrasting with the emergence hole left by Trogus and close allies.

Field surveys at four neighbouring but discrete sites in southern France revealed the presence of five ichneumonid parasitoids of the Lathyrus-feeding sterictiphorine argid sawfly Aprosthema tardum. Four of these parasitoids, Lathrolestes erythrocephalus, Ischyrocnemis goesi (both Ctenopelmatinae), Terozoa quadridens and Thibetoides aprosthemae (both Tryphoninae), could be identified and, by also incorporating laboratory studies, the developmental biology of each was elucidated and illustrated. A little supplementary information from a site in Italy is also presented. The fifth species was detected only once and failed to develop in its cocoon; it remains unidentified but the cephalic sclerites of its final instar larva are illustrated. The identified parasitoids are all more or less rare and little-known species and prior to this study only L. erythrocephalus had a known host; the others were biologically unknown even at the generic level and not recorded from France. The egg of L. erythrocephalus bears prominent hooked structures at its capital end, not reported in other studied Lathrolestes species. From its biology as an endoparasitoid of a sawfly and from larval characters, Ischyrocnemis is confidently assigned to Ctenopelmatinae. Both ctenopelmatines could successfully parasitise the host during any of its 2nd to 5th instars, but the tryphonines were less flexible. Terozoa monitors hosts until the moult to the final instar before ovipositing on them, usually affixing the egg to the head and often an eye (stemma), while Thibetoides parasitises much younger hosts, placing its strongly anchored egg behind a thoracic leg where it remains through successive host moults. Some characters used in the past to determine Terozoa species are discussed, and a new provisional key to the known species of Terozoa is presented. The very different developmental biology of Terozoa and Thibetoides may challenge views that they are closely related genera. Terozoa bituberculata (Constantineanu, 1973), stat. rev. is raised from synonymy with T. quadridens Perkins, 1962. Reinterpretations of several cephalic structures of final instar larvae as well as larval spiracles are discussed, and a new interpretation and terminology for describing the latter is introduced.

Data on Coelopisthia pachycera, C. extenta and C. areolata in France are presented including a rearing record for C. pachycera from Maniola jurtina. Elsewhere in Europe C. pachycera has been reared from pupae of M. jurtina and other species of Nymphalidae.