The Open Door Web Site
Part XV : Animal Dispersal Index
This mature adult has wings and can fly long distances. Note: The adult and the larva in these photos are not of the same species.
Changing Shape to Travel Better : Insects
Most invertebrates, however, are small and moving from one place to another can be difficult and dangerous. Many invertebrates (including insects and crustaceans) solve this problem by having at least two different stages in their lives - an immature, or larval stage, and a mature, adult stage.
Most insects show these two stages in their life cycles. Since the majority of adult insects have wings, it is this stage which is responsible for dispersal. It is easier to fly through the air than to crawl through grass and leaf litter or to burrow through the soil.
The adult insects are capable of reproducing. After mating the female will lay eggs on a suitable food supply for the larvae to eat when they hatch'. This food supply may be some distance from where the adult female spent her larval stage.
Once hatched from their eggs, the larvae eat and grow. Eventually, they prepare for the change into the adult stage. This change often takes place in a special structure called a pupa.
The larva constructs the pupa around it when it is ready to become an adult.
Cabbage plant destroyed by larvae
Detail of larvae on cabbage plant
The life cycles of these insects are not only adapted for dispersal. They also help insects to survive the cold weather during the winter months. Most adult insects die as the cold weather sets in. The insect species, however, survive either as eggs, larvae or pupae. The eggs and pupae are hidden in places protected from the cold. The larvae can move to protect themselves. Some burrow deep into the soil where the frost and ice do not penetrate.
A pupa attached to the bark of a tree
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