Aphids on my Apletree :(

Aphids - Family Aphididae

Aphids are small to very small in size. They are soft body and usually wingless. Usually their body is in pear-shaped. Most species have a pair of posterior at the abdomen.
Like most other bugs they are sap-sucking insects. Unless aphid colonies are allowed to grow to a large side, the feeding activity of a few aphids will cause little damage. The real problem is if the aphids carry a plants virus which infected the plants.

Aphids are different from most other insects in two ways. Firstly, all aphids in the colony are female and reproduce without the male. Secondly, females aphids give birth live young on the same plants and form a colony.

In most of the time Aphids are wingless. Sometimes, usually in spring and autumn, winged aphids appear and they find new plants to start new colony.

Aphids have the ability to reproduce rapidly and there are many generations per year. A female in general produce 100 nymphs in 30 days. Each new born take about a week to become an adult and start reproduction.

Aphid populations are growing rapidly during the spring season. Reproduction is high because they can get enough food from the plant that grow most rapidly. After the spring season, predators and parasitoids start to grow and reach a level to suppress the aphids.