This is a small family with hosts in the Diptera, Hymenoptera, Lepidoptera, Coleoptera and Homoptera. They are more generally found as secondary external parasitoids of Aphididae and dactylopine Coccidae, through Braconidae and chalcidoid primaries. Calliceras abnormis Perk. attacks mature dryinid larvae in their cocoons in Hawaii, and Lygocerus semiramosus Kieff, is a secondary parasitoid of Chermidae through Encyrtidae in India (Clausen 1940/1962).
Biology & Behavior
Lygocerus cameroni Kieff. is a secondary parasitoid of aphids through aphidius spp. (Haviland 1920). It attacks mature larvae and sometimes early pupae of Aphidius and also may develop on corresponding stages of its own species. It is solitary and external. Oviposition occurs only after the body contents of the aphid have been completely consumed by aphidius and only the shell remains, which is lined with silk by the mature larva of the primary parasitoid. Females may either stand on the aphid body during oviposition or insert their ovipositor by a backward thrust. The egg is laid on the dorsum of the body of the aphidius larva or pupa. The meconium is cast by the prepupa, appearing as a single black spherical mass lying in the mid-ventral curve of the pupa. The cycle from egg to adult is complete in 21-24 days, of which the egg, larval and pupal stages take 1, 6-7 and 14-16 days, respectively. The number of eggs per female was estimated at not more than 25, and the sex ratio was ca. 1.5:1 in favor of females.
Spencer (1926) studying L. niger How. found that the host preferences and habits are similar to those given for L. cameroni. Development takes place occasionally on its own larvae also. The egg is placed somewhat ventrally, rather than dorsally, on the Aphidius larva of pupa. The body of the pupa is curved ventrally into a semicircle, and the single meconial pellet lies at the middle of the curve and is encircled by the antennae for 3/4ths of its circumference. The cycle from egg to adult takes an average of 14 days. There is no thelytoky known.
The genus Lygocerus is also hyperparasitic on mealybugs. Lygocerus sp. is a secondary parasitoid of Pseudococcus sp. through the encyrtid, Clausenia purpurea Ishii, in Japan. Attack is limited to pupae, and it was not possible to secure oviposition on mature larvae. Due to the host cell's ellipsoidal form, the pupa is fully extended rather than curved as described for L. cameroni, and the single meconial pellet lies at the tip of the abdomen. Withycombe (1924a) found a female of Lygocerus sp. to bite a hole in the cocoon of Conwentzia psociformis Curt. before depositing her egg (Clausen 1940/1962).
A conical process on the last abdominal segment of the larva of L. cameroni, which occurs in other species of the genus, is believed to serve for locomotion (Haviland 1920). There really does not seem to be a need for locomotion in confined quarters that the larva occupies, but the exceptional mobility of the posterior portion of the body, observed in Lygocerus sp., supports this assumption. The movements of the tapering abdominal end of the body suggest those of the head and thorax of syrphid larvae when searching for food (Clausen 1940/1962).
Two species of Conostigmus reared by Kamel (1939) were C. zaglouli Kamal and C. timberlakei Kamal, taken from puparia of Syrphidae in California. These are gregarious external parasitoids on the pupa within the puparium. Eggs are laid on the integument of the newly formed pupa and hatch in 2 days. The larval period is long, covering ca. 24 days, and the pupal period is 6-8 days. The cycle from egg to adult requires slightly more than 1 month. Mature larvae of C. zaglouli may go into diapause for several months under adverse conditions. The meconium is in the form of a large number of minute pellets rather than a single spherical mass such as found in Lygocerus. A maximum of 33 individuals were reared from a single puparium.
Most if not all members of the family develop externally, although within the cocoon, puparium, or dead body of the primary of secondary host. There is no case in which attack is on naked larvae or pupae.
For detailed descriptions of immature stages of Calliceratidae, please see Clausen (1940/1962).