The Open Door Web Site
Part XVI : Seasonal Changes in animal Populations
SEASONAL CHANGES IN ANIMAL POPULATIONS
Insects in Spring
Many people think that at the end of summer all the insects die. Obviously, this is nonsense. Where would the insects that are seen in springtime come from? Many insects pass through winter in a resting stage, as eggs or as pupae. Insects, such as dragonflies, have larvae called nymphs which are aquatic (meaning they live in water). These nymphs can remain quite active during the winter period, as long as the water does not freeze.
Only the adult insects are sexually mature. In springtime the eggs and pupae, which have spent the winter in a dormant state, complete their development. The adults which emerge from the pupae lose no time in finding mates.
Most adult insects have wings and, before she lays her eggs, the female may fly quite a distance to find a suitable supply of food for the next generation. This helps to disperse the species.
The majority of insects metamorphose as shown by the following life cycle of the cabbage white butterfly.
The larvae are sexually immature. Their function is to eat and grow. They need to shed their skin a few times in order to increase in size. This is called moulting. At the final moult, the skin becomes hard as the insect enters its pupation. Inside the pupa the tissues of the larva are broken down and re-arranged into the adult form. After a certain period of time, which may be over the winter months, an adult insect emerges from the pupa. The cycle is now complete.
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