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How to recognise it
Capsid bugs are small (up to 6mm long) insects which vary from pale yellow and green to red/brown in colour. The adults are winged but the nymphs are wingless. You may spot the bugs on the plant, but they are very timid and usually drop to the ground or fly away when disturbed.
The damage caused usually appears as small, ragged, brown-edged holes appearing in young leaves, which then become tattered as the independent holes ‘join up’. Leaves can also appear distorted or ‘puckered’. Damage may be seen on buds and shoots.
Lifecycle
The lifecycle varies between species. Eggs hatch in spring and nymphs feed from late spring through summer, maturing into the winged adults. There may be more than one generation each year. Capsid bugs overwinter either as eggs or adults (depending on the species).
Why it’s a problem
Both the nymphs and adults feed off the sap of plants, piercing the plant and injecting saliva, which kills plant tissues (causing the irregular holes), before sucking out the sap. This results in the eventual disintegration of affected leaves, the death of buds and shoots, and any flowers developing from affected buds being deformed. Fruit produced (eg apples) can have bumps or other irregularities as a result of the infestation, but is still edible.
Where you are likely to find it
The damage from capsid bugs is generally most noticeable from late spring through summer and they can attack a very wide range of garden plants. Some of the principle plants affected include apple trees, currants, hawthorns, potatoes, pears, plums, gooseberries, rapsberries, strawberries, runner beans, asters, arctotis, buddlejas, caryopteris, ceanothus, chrysanthemums, dahlias, forsythias, fuchsias, hydrangeas, magnolias, nasturtiums, pelargoniums, poppies, roses, salvias, sunflowers, venidiums and zinnias.
How to deter it
Clear up debris and fallen leaves in winter, particularly under hedges, which may be providing overwintering accommodation for the eggs or adults. Keeping weeds to a minimum will also remove any alternative hosts for this pest.
How to get rid of it
This isn’t usually serious enough to merit chemical treatment (particularly not on vegetables), but if the damage is particularly unsightly or affecting soft fruit crops, an insecticide such as pyrethrin, a synthetic pyrethroid compound such as bifenthrin, or thiacloprid can be used on the plant and surrounding ground (to include bugs which drop off the plant when disturbed). This can be done on woody plants (which may harbour overwintering eggs) in December or January when the plants are dormant, but this will not protect the plants from re-invasion in the spring, so spraying these, and herbaceous plants, in May, June and July when the pests are active will be more effective. Spray strawberries, raspberries and loganberries immediately before flowering and apples, pears, plums, currants and gooseberries immediately after flowering. Ornamental plants should be sprayed in spring and summer and may need a further application later in the year.
Is it good for anything?!
Some species of capsid bugs feed on other creatures which are considered pests, including caterpillars, mites and aphids.
Other useful information
More detailed information is available about the Common green capsid – Lygocoris pabulinus.
