Are small, soft-bodied insects which are usually 2–4 mm long. They often cluster on young shoots and flower buds or underneath older leaves. There are many different species of aphids, varying in colour from green to yellow and black.
Aphids excrete a substance called honeydew, which provides a growing environment for sooty mould fungus. Aphids can also transmit virus diseases such as broad bean wilt. It’s important to remove these pests as soon as you notice them on your plants, because small colonies multiply rapidly in warm weather, and large infestations can develop in a number of days. Check your plants a couple of times a week at the beginning of warm weather, so that aphids can be controlled when populations are relatively small.
Symptoms include buds failing to open, and twisted and distorted leaves.
Aphids can be removed either by blasting them off with water, or using predatory bugs such as ladybirds and parasitic wasps. The tiny wasp lays eggs inside the aphid giving it a hard light brown shell-like appearance. The ladybird larva, which looks like tiny bird droppings, is a voracious eater of aphids. Both of these predators will reduce aphid numbers rapidly.