Sap sucking insects and what to do about them

Sap sucking insects, as their name suggests, suck the sap out of plant leaves leaving them at best pale and spotty and at worst, having devoured all the chlorophyll, white, dry and lifeless.

There is a large range of sap sucking insects including aphids, leafhoppers, stink bugs, mealy bugs, thrips, white fly, scale, and spider mites to name just some. Not only do they suck out the sap but also they transmit disease (bacteria and viruses) and affect the vitality of the plant and sometimes cause deformity in the fruit.

The presence of ants, sooty mould, leaf curling, leaf yellowing as well as pale and spotty leaves all indicate the presence of sap sucking insects.

The best way to deal with sap sucking insects is with natural predators such as ladybirds, lacewings, praying mantises and parasitic wasps. To encourage these into your garden, plant as much biodiversity as you can. The greater the variety of plants you have the better.

Other things you can do are to improve your soil. Healthy soil full of microorganisms will mean plants are healthy and less vulnerable to attack. Weaker plants or those that are dying off are most attractive to sap sucking insects. Make sure your plants (and therefore soil) are well watered so that they are resilient. Avoid using insecticidal sprays as these kill the sap sucker insects’ predators and can wipe them out. They will return at a slower rate than sap sucking insects, creating an imbalance and making the problem worse.

Written by Robin Gale-Baker