Are sap suckers and as such can also be disease vectors, they are also called 'greenfly'.

although they can be a bad pest of plants, they have many predators and chemical controls often kill the predators as well as the pest itself.

Dislodging the insect with a strong squirt of water from a hose is effective, as aphids are poor walkers.

Sprays include white oil and pyrethrum.

Whitefly resemble tiny white moths that rise in a cloud if present on plants and disturbed.

Adults resemble scale and are found on the underside of leaves.

Like many scale insects they produce honeydew and so are often associated with ants.

Symptoms include yellowing and wilting of leaves if numerous.

Also sap suckers, infestations can become so severe that the insect competes with the plants for its food and can cause weakness. Soft scale is associated with sooty mould - a black mould that grows on the sticky
honeydew excreted by the scale.

This mould can interfere with plant growth. Ants are almost always associated with insects producing honeydew and will fend off predators to farm the sweet excrescence.
Small infestations can be controlled by hand removal. Extensive outbreaks should be treated with a spray such as a combination of white oil and maldison.

Caterpillars are the larval stage of butterflies and moths. If we are to enjoy the beauty of butterflies in our garden we must be selective about how and which caterpillars we kill. Single large caterpillars are usually only temporary in their presence and perhaps can be tolerated if they aren't eating the whole crop!

However, there are plenty of caterpillars that are social and can eat out large numbers of leaves if not controlled. Hand removal is the best control method, spraying of Maldison of Carbyl will kill most caterpillars if there is no alternative.

A number of insects are associated with the formation of galls on leaves, which appear as raised hard bumps or warty outgrowths.

The effect is more disfiguring than any adverse impact on the health of the plant and as such only require treatment if the infestation is very severe.

Removal and disposal of affected leaves is the best control for this common pest.

Scribble like marks are the feeding tunnels of a tiny larvae that lives within the leaf.

Again, no control is really necessary, other than removal of affected parts, unless the infestation is very severe.

If spraying proves necessary, a penetrative poison such as dimethoate is required

Are most active in warm weather and prefer a moist environment. They leave telltale silvery trails and can eat a crop of tender shoots overnight.

They have not been found to be much of a problem in the Trees for Survival shadehouses, probably due to the raised benches that seedlings are stored on and the open nature of the construction

Once your seedlings are established, snails and slugs pose very little threat, although they can be a slimy surprise when picking boxes or items off the ground that have been gathering moisture and decaying plant material.