The adults are short-lived and are seldom seen in large numbers. Alderflies are active during the warmest parts of the day and sometimes fly for very short distances. Most dobsonflies and fishflies are active at night and are attracted to lights. Their flight is slow and awkward, but they are capable of covering long distances.
Some alderflies and dobsonflies locate their mates with pheromones (FEH-re-moans), or special chemicals that attract males as mates. Male dobsonflies have very long jaws, which they use to battle other males over females. Males place their jaws over the wings of the female for a short time before mating. Megalopterans usually mate on plants near the water.
The life cycle of megalopterans includes four very distinct stages: egg, larva, pupa, and adult. Females attach layered masses of two hundred to three thousand eggs on objects that hang over the water. They usually select mostly shady sites that are pro tected from direct sun during the hottest time of day. The larvae drop into the water after hatching. They will molt, or shed their ex-oskeletons or hard outer coverings, ten to twelve times over a one- to five-year period before reaching the pupal stage. Mature larvae leave the water and pupate in a chamber dug in the soil or leaf litter near the shore. Adults usually emerge in late spring to midsummer and live for only a week or two.
The legs, wings, antennae, and mouth-parts of all megalopteran pupae are distinct. These appendages are not attached along their entire length to the body. The pupae are also not enclosed in a cocoon.
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