Tenthredinidea, Stirps 2 Leach, 1817: 115.
Tenthredinetae, Div. h Lepeletier de Saint-Fargeau, 1823: 40.
Perginae Ashmead, 1898: 229, 231-232.
Syzygoniides (pt.) Konow, 1905a: 10, 11-12.
Pergidae Rohwer, 1911a: 226.
Westwood 1880 [diagnosis, description, key to species, new taxon, revision/review, systematics – classification: 359-379, pls xxxiv-xxxvii]; Kirby 1882 [new taxon, systematics – classification: 18-30]; Shipp 1894 [key to genera, systematics – classification: 338-340]; Ashmead 1898 [key, key to genera, new taxon, systematics – classification: 228, 229, 231-232]; Konow 1905a [host plant, key to genera, systematics – classification: 3, 11]; Froggatt 1907 [description: 71-72]; Rohwer 1911c [key, systematics – classification: 218, 226]; Morice 1919 [systematics – classification: 329-331]; Allen 1920 [rearing: 159]; Benson 1935 [description of adult, distribution (range), key: 223]; Ross 1937 [phylogeny: 37-38]; Benson 1938c [distribution (range), key: 378, 379]; Benson 1939 [key to genera, new taxon, revision/review, systematics – classification: 324-356]; Riek 1970a [key: 218]; Riek 1970b [behaviour, host plant, stridulation: 882]; Smith 1978 [catalogue/checklist: 135-147]; Naumann 1991 [behaviour, distribution (range), economic importance, host plant, key: 934-935]; Macdonald & Ohmart 1993 [behaviour, behavioural defence, development, host plant, illustration of immature stages, life history, oviposition: 487-489, 496]; Schmidt et al. 2006 [behaviour, host plant, oviposition: 187-188].
A detailed description of the biology of Perga affinis was given by Carne (1962). Larvae feed at night and rest in a cluster during the day (Macdonald & Ohmart 1993). Larval clusters can contain more than one pergine species (Carne 1962). Meyer-Rochow (1974) investigated vision of larvae of Perga affinis, Pergagrapta turneri, and P. bella: they are probably capable of discerning shape; the sensitivity is increased at night and they can increase sensitivity by 2 to 3 log units in the dark without losing resolution. For pupation larvae go into the ground as a group where they construct double-walled cocoons in a honeycomb fashion side by side (Macdonald & Ohmart 1993). The prepupal moulting occurs in the cocoon. Parasitism by mermithid nematodes has been observed (Macdonald & Ohmart 1993). Major parasitoids of Perginae are Trigonalidae, Ichneumonidae, and Tachinidae, and they can cause high levels of mortality (>80%, Macdonald & Ohmart 1993). When disturbed larvae exudate a fluid from their mouth trying to apply it to their enemy. This fluid is stored in a large sac, the pharyngeal diverticulum, and consists of essential oil of the host plant on which the larvae feed (Morrow et al. 1976, Schmidt et al. 2000). Larvae possess an external morphological modification of the mandible, the ‘scopa mandibularis’, that apparently serves to separate toxic leaf compounds from nutritive parts of the leaf (Schmidt et al. 2000). The discharge of oral fluid has been regarded as defence behaviour against natural enemies (Carne 1962, Morrow et al. 1976), but the observation that larvae empty their diverticulum even without being disturbed suggests that it is a mechanism to avoid potentially toxic essential oils of the host plant (Schmidt et al. 2000).