Tachinid flies are not well known at the species level in America north of Mexico. Though the number of species described probably accounts for 80-90% of the total number of species in the region, few keys are available to distinguish them. It is estimated that less than 20% of the species in America north of Mexico can be reliably keyed. Consequently, almost all species identifications depend on comparisons, by a specialist, of unidentified specimens with previously identified museum specimens. The family Tachinidae is the most important family of parasitic flies providing biological control. Tachinid larvae are internal parasites of immature beetles, butterflies, moths, sawflies, earwigs, grasshoppers, or true bugs. Adults measure between 3 and 14 mm (<1/2 inch), are often dark, robust, hairy and resemble houseflies, but with very stout bristles at the tips of their abdomens. Egg laying varies considerably. In some species, eggs are deposited on foliage near the host insect, and the maggots are ingested during feeding by the host after they hatch. In other species, the adult fly glues eggs to the body of the host, and the maggots penetrate into the host's body after the eggs hatch. Some female tachinids possess a piercing ovipositor and insert their eggs into the host body. In all cases, tachinid maggots feed internally in their hosts and exit the host body to pupate. Pupae are commonly oblong and dark reddish. Tachinid flies complete one to several generations per year.