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Order
- MEGALOPTERA
(Greek, megas = large; pteron = wing)
Common Names: alderflies, dobsonflies,
snakeflies
Distribution: Best represented in temperate
regions
Description
The Order Megaloptera includes the snakeflies which some entomologists
consider should be placed into the separate Order Raphidioptera. Still
others are of the opinion that both these Orders should be placed within
the Order Neuroptera. Megalopterans are soft-bodied insects with two pairs
of delicate, large, finely veined wings. Often the wings are so long that
they extend well beyond the abdomen. The antennae are long and composed of
short, straight segments (filiform). The compound eyes are separate and
well developed. Mandibles are prominent. The snakeflies are distinguished
by having a "sit and wait" hunting technique similar to praying
mantids, however, the spiny forelegs are not present. Instead the head is
very mobile and is shot forward (as in the head of a striking snake) so
that the jaws can grasp the prey. Alderflies and dobsonflies have well
developed mandibles, but do not feed in the adult stage.
Larva
The life cycle is metamorphic: egg-larva-pupa-adult. All stages in
snakeflies are terrestrial, but alderflies and dobsonflies have aquatic,
gilled larvae. Freshwater streams are utilised, preferably with clear,
running water. The larvae move over the floor of the stream and when
mature pupate under rocks on the stream bed. Adults of some aquatic
species take wing at or near dusk and fly about over the water surface.
Members
Alderflies, dobsonflies, snakeflies.
Food
Megalopterans feed on insects or other arthropods, whether aquatic or
terrestrial. Both larval and adult snakeflies feed. However, adult
alderflies and dobsonflies do not feed.
Importance
Megalopterans role as fish food in streams is extremely important.
Alderflies and dobsonflies have larvae that are very intolerant of
pollution and their presence in a stream is therefore a good indicator of
its health. |