Immature Stages of Hemerobiidae
Detailed information on immature stages of Hemerobiidae is being acquired. However, Clausen (1940) noted that all species were predaceous attacking mainly aphids, but also chermids, mealybugs, white flies and sometimes diaspine scales. Withycomb (1922, 1923) found that the eggs in all species are laid on the side. They are whitish, grayish or even pink and elongated oval, with the chorion frequently pitted, and bearing a knob-like or disk-like micropyle, often of great size. In Wesmaelius the chorion is densely studded with glossy papillate projections. The egg breaker is shaped like a saw. The eggs of Hemerobius pini are pale cream in color, but change to brown before hatching.
There are 3 active larval instars, which are similar to the larvae of Chrysopidae. Only the 1st instar larva has a trumpet-shaped tarsal claws, while they occur on all instars of Chrysopidae. The cocoons of this family differ markedly from the nearly spherical parchment-like ones of Chrysopidae, being loosely woven, double-walled, and elliptical. They are usually found in protected places rather than exposed on the foliage or bark. The pupal skin is cast outside the cocoon.