All Epipyropidae are true parasites (not parasitoids) mainly on Homoptera of the family Fulgoridae, and occasionally from Cicadellidae and one species occurs on Cicadelidae in Japan. The family is abundant in Australia, Perkins (1905b) having observed millions of cocoons on the foliage of Terminalia in Queensland, which gave the appearance of a heavy infestation of Pulvinaria. A number of species occur in India also. Westwood (1876) observed larvae of Epipyrops anomala Westw. on the bodies of Fulgora candelaria L. and concluded that they were feeding mainly on the cottony secretion covering the body of this insect. The larger larvae of E. fuliginosa Tams scraped the side of the host body with mandibles, probably feeding on secretions (Subramaniam 1922). No injury seemed to be inflicted, and the leafhoppers looked healthy long after the larvae had abandoned them. However, later observations by various researchers showed that the larvae of some species are definitely parasitic and that the scraping and removal of wax are incidental to the efforts of larvae to penetrate the host body wall. Clausen (1940) stated that one of the main arguments to support a parasitic relationship is that fact that the hosts of some species have no wax body covering. In such cases it was asserted that feeding may take place on the honeydew, which is produced in abundance. The larvae have very long slender mandibles more fitted for penetrating the body wall than for use in feeding on external secretions (T. B. Fletcher cited by Clausen, 1940).
Krishnamurti (1933) studied E. eurybrachydis Fletcher, that develops as a solitary or gregarious external parasite on the adult females of the fulgorid, Eurybrachys tomentosa F. in India. Nymphs or male adults are not attacked. The eggs are a dirty gold-yellow, oval in form, and measure 0.5 mm. long. They are laid in series of irregular rows on the foliage of the host's food plant. Each female produces a total of 400-500 eggs. Incubation is complete in 6-8 days, and the young larvae wander about on the foliage in search of hosts. They are often observed in an erect position, clinging to the leaf margins by the prolegs, and waving back and forth as if waiting for a host. There are 5 larval instars, the 1st of which is 1.25 mm. long with 13 body segments which decrease in width toward the back. The legs are short, 5-jointed, and end in a curved claw; mandibles are bidentate. Younger stages are found on different parts of the host body. Older individuals are usually beneath the wings, at one side of the median line, and they lie with the head directed toward the back. The presence of one of these parasitic larvae on the fulgorid body is always indicated by the elevated position of the wing on one side. The mandibles are embedded in an aperture in the abdominal integument. The effect of parasitism on the host is slight, for the amount of body fluids abstracted is comparatively small in relation to the size of the host and is manifested only by a small amount of weakness. Adult life is not much shortened, nor is egg production reduced. The parasite's larval feeding period is 42-45 days and adult life 8-10 days. When feeding is finished, the mature larvae, not 7-8 mm. long, leaves the host and spins its oval, milky-white cocoon on the underside of a twig. The pupa emerges partly from the cocoon just prior to the issuance of the adult moth, and oviposition begins 24-36 hrs. after emergence from the cocoon.
Other species that have been studied in smaller detail are Agamopsyche trenodes Perk. (Perkins 1905b) and Epipyrops doddi Roths. (Rothschild 1906). There is considerable variation with regard to the sex and stage of the host attacked. A. trenodes attacks the adults of both sexes of Cicadellidae. However, other species of the family have been found on nymphs as well as adults (Perkins 1905b). Feeding of the larvae seems to produce little or no effect on the host. However, in A. trenodes the parasitized leafhoppers show a distinctive collapse of the abdominal dorsum, and death may occur the day following the departure from the host (Clausen 1940, citing Koebele). This is also thought to be true for E. barberiana Dyar, developing on Ormenis pruninosa Say in North America.
Epipyrops larvae assume a rather uniform position on the body, this being on the dorsum of the anterior portion of the abdomen beneath the wing, and with the head directed toward the rear. The tip of the abdomen in E. fuliginosa is apparently attached to the side of the host thorax. Epipomponia nawai Dyar, attacking adult Cicadidae in Japan, is small compared to the host and is found on the thoracic venter or on the venter or dorsum of the abdomen. The fact that the larvae retain a fixed position on the host further supports the true parasitic relationship (Clausen 1940/62).
The disk-like eggs of Agamopsyche are laid in large batches on dead grass and leaves in the same environment in which cocoons are found (Perkins 1905b). However, there is little doubt that the eggs of other species are also laid in clusters on foliage or twigs in the vicinity of feeding hosts and that the 1st instar larvae either search for their hosts or wait until they pass nearby.
There is a relatively short life cycle, from egg to adult of ca. 1 month. About half of this time is spent as larval feeding. The cocoon stage of E. doddi takes 13-17 days and that of E. anomala 9 days. Perkins (1905b) found that Agamopsyche is unisexual with no males known. Fertile eggs were produced by virgin females under cage conditions. However, males are known in species of several other genera.
First instar larvae of Epipyropidae have adaptive characters developed as a result of their unusual life style. The very slender, tapering body with comparatively strong legs, is obviously an adaptation to free-living during the host searching phase. This larva shows a tendency towards assuming a planidium form found in other orders, which has been developed to meet very similar requirements. It is able to stand erect by the use of anal prolegs, a behavior that is general among larvae of this type in many other families and orders (Clausen 1940/62). After the first molt, the legs become much reduced and the later instars are almost sessile. The head and mouthparts of all instars are markedly modified as a result of the manner of feeding. The body becomes either oval or almost circular in outline, and a distinctive form is assumed. This is accentuated by the presence of an extensive waxy covering over the body. In Agamopsyche, it was observed that the larger larvae were able to suspend themselves from the host body by a silken thread. The cocoons are white, with a mealy surface. There is considerable variation in form and surface ornamentation. Usually there are many longitudinal ridges. The cocoon of an undetermined species of epipyropid was observed by Koebele in Australia was rosette-like and nearly circular, with several vertical lamellae arranged concentrically about the more solid center. The empty pupal case is found partly extruded from the cocoon (Clausen 1940/62).