All ichneumon wasps are parasitic like the braconids, and they feed on many of the same hosts-especially larvae of the spruce budworm and leaf roller. These insects are actually beetles not flies. Males are the conspicuous sex, with their illuminating body organs. Females and the larvae form can be luminous, and are referred to as glow-worms. Both adults and larvae are insect predators, feeding on snails, slugs and many other insect larvae.
Fireflies are nocturnal for the most part, and are usually only seen at night.
Adult beetles are only about 15 mm. The adult fly is about 15 mm. Host insects include larvae of many moths, butterflies, beetles, and especially sawfly larvae. Adult flies are often seen in flowers feeding on the nectar. They also consume honeydew secreted by various other insects, and then often parasitize the insect that produced the honeydew.