The habits of Lepidoptera larvae are very diverse. Most of these larvae are leaf eaters, but some bore into trunks of trees and stems of herbaceous plants. Some of the small ones mine within leaf tissue, others live in the ground, where they eat roots, and a few are aquatic, living in clear, rapidly flowing streams.
Diptera
Flies, Mosquitoes, and Their Allies
Insects with only one pair of wings, each wing with a limited number of veins. Other characters of the order, including antennae and mouthparts, are extremely varied. Most immature stages are wormlike or maggot-like. They live in protected situations, such as within the tissues of a plant, in water, in leaf mold, or in the tissues of animals. A typical life cycle is that shown for the house fly, Musca domestica Linnaeus, [fig. 65]. The ubiquitous house fly is undoubtedly the best known representative of this order. It is also one of the most persistent and dangerous insect pests, being a possible carrier of many diseases.
Fig. 65.—Diptera. Musca domestica, the house fly. The fly has only a single pair of wings; the pale, maggot-like larva is without legs; the darker, egg-shaped puparium contains the pupal or quiescent stage. Length of adult 0.2 inch. (Drawing by Alice Ann Prickett.)
Mosquitoes, punkies, black flies, and horse flies are likewise well known members of this order. In addition to economic forms, the order Diptera includes midges, crane flies, bee flies, robber flies, bluebottle flies, and a great assortment of other kinds of insects. Interesting are the bee flies, which mimic other insects such as honey bees, bumble bees, and wasps to an extent that wins them immunity from the attention of many beginning collectors.
Siphonaptera
Fleas
Wingless insects that evolved from folding-wing insects; conspicuously flattened from side to side; with stout spiny legs, and with numerous spines over the body; without conspicuous antennae or tails or a forked posterior appendage like that of the springtails; usually hard; ranging in color from yellowish brown to almost black.
The human flea, Pulex irritants Linnaeus, and a widespread Illinois rat flea, Nosopsyllus fasciatus (Bosc), are shown in [fig. 66].
All the fleas, which feed on the blood of birds and other animals, have sucking mouthparts. They are powerful jumpers. The young stages are slender, white larvae, [fig. 67], which live in the nests of various animals; these larvae are seldom collected. The fleas are found on the animals themselves or around their nests. Several species of fleas, including the cat and dog flea, the human flea, and the rat fleas, attack man. One of the rat fleas, Xenopsylla cheopis (Rothschild) is the common transmitter of the organism causing bubonic plague.