Damage Depending on the species, aphids can cause various types of damage to crops:

• they suck sap from the plant, reducing growth rate
• the excess sugar they absorb is secreted as honeydew, making the leaves and fruits sticky and encouraging the growth of sooty moulds
• they can transmit viruses, such as the cucumber mosaic virus (CMV)

Control
It is difficult to identify aphid species, even with a hand lens, so we offer a mix of natural enemies designed to control the common species of aphids found on edible glasshouse crops.

It is also difficult to spot aphids when the numbers are low, so we recommend that you introduce the product at the same time as you plant your up greenhouse. A female aphid produces up to 100 live offspring, so numbers can rapidly increase.

The mixture includes a tiny parasitic wasp called Aphidius which can locate new aphid colonies even when the population is low; it can lay an egg in about 100 aphids.

The larva develops and pupates inside the aphid. The dead host aphid becomes a golden-brown ‘mummy’ from which the adult wasp emerges by cutting a tiny exit hole. The empty mummies remain on the leaf surface, so you can see that the product is working.

How to use
The eggs are supplied in a cardboard tube including food. The parasites will emerge over a period of around 21 days. If you have already found aphids in your crop, position the tube on the plant, near and slightly below the pest. It is important that the tube is in the shade and doesn’t get wet when the plants are watered.

Order by Thursday midday for the following week (usually dispatched on Wednesday to arrive Thursday).