Matriarchal society aphid style

We have begun our battle with the battalions of gardening saboteurs. The slugs and snails have munched their way through lettuce seedling and the mice have dug up the sweet pea seeds.

The next battalion to move in will no doubt be made up of some members of the 500 species of aphids found in Britain. Commonly called greenfly they actually come in an array of colours, green, pink black, white and no doubt other colours too. Many are visible on our plants and other lurk underground feeding on roots.

At this time of year eggs that have overwintered hatch. The hatching is well timed to take advantage of the emergence of tasty new shoots. In also coincides with the time that the birds are hunting for insect food for nestlings, just one good reason for not resorting to spraying. Early greenfly colonies on our roses are made short work of by our garden allies. We often see birds foraging for aphids in the branches of the fruit trees on the plot too.

The newly hatched aphids or nymphs are all females and are just smaller versions of their mothers. As with other insects as the nymphs grow they shed their skins. A week after birth they are fully mature and capable of reproducing. They do this without any need to mate. In some species aphids are actually born already carrying another generation.

The females can give birth to five live young each day for a period of about thirty days so it is easy to understand why infestations build up so quickly. If all offspring survived, a single female could be responsible for a line of aphids 27,950 miles long,

If a food supply is no longer capable of sustaining the colony, it triggers the production of winged females. These individuals are not capable of strong flight but can be carried long distances on the wind. When they land on a suitable food supply they will start a new colony.

The cycle continues all summer until temperatures fall. Around October, winged males are produced. Their only purpose is to mate with winged females. Once mated the females deposit eggs in a safe place to overwinter and so the circle is completed until the following spring when it all starts again.

Aphids belong to the bug family and feed by piercing the plant with a feeding tube through which they draw sap from the plant. Feeding aphids can cause leaves and buds to become deformed and they can also transmit viruses and disease from one plant to another.

Aphids ingest more sugar than they need and any excess is passed out through two tubes at their rear end. This sugary substance or honeydew causes plant leaves to become sticky and forms an ideal feeding site for sooty mould which coats the surface of the leaves with a black fungus. Although the fungus doesn't harm the plant it does stop light reaching the leaves and prevents the plant from producing food.The overall result of an aphid infestation is a weak and struggling plant.

Aphids do have an unlikely ally. Ants love the honeydew produced by aphids and will protect aphids from their enemies so that they can maintain a flock of honeydew producers. Some ants even farm aphids but that's another story. 

Fortunately we have many allies in our war against aphids so we need to take care that our attempts to control aphids don't inadvertently harm our garden friends.

If you are interested I have written on aphids in a little more detail on our website here.