Earwigs and ants

Two reputations, both largely undeserved

Earwigs and ants between them account for a great deal of garden anxiety and very little garden damage. Both are worth understanding before doing anything about either, because in most gardens the correct response to both is to leave them where they are.

Earwigs

A shiny reddish-brown insect about 15 mm long with a pair of curved pincers at the rear end. It hides by day in anything dark and tight, which is why one falls out of a cut dahlia on the kitchen table, and feeds at night.

What it eats is mostly other insects. Aphids, woolly aphid, pear sucker, mites and the eggs of codling moth all feature heavily, and research in commercial orchards has repeatedly found earwigs to be among the most valuable predators an apple or pear tree has. Growers now put shelters up to encourage them.

They also chew petals, particularly on dahlias, chrysanthemums and clematis, and they will enlarge existing damage in soft fruit and ripe apples. On a plant grown for its flowers that matters, and it is close to the whole of the case against them.

The sensible response, where it matters at all, is to move them rather than kill them. An upturned pot stuffed with straw on a cane among the dahlias fills with earwigs by morning. Tip it out under the apple tree. The blooms are protected and the orchard gains.

The pincers cannot break human skin, and the name comes from an old belief about ears that has nothing behind it.

Ants

Ants do not eat plants. Nothing about an ant is equipped to.

What they are doing on a stem is collecting honeydew, the sugary liquid that aphids, scale insects and other sap-suckers excrete. The relationship is a managed one: the ants take the honeydew, and in return they drive off ladybirds, lacewing larvae and hoverfly larvae that would otherwise be eating the aphids. Some species move aphids to better feeding sites and overwinter them in the nest.

The consequence for the gardener is real but indirect. A farmed aphid colony grows faster and lasts longer than one being predated, so the plant suffers more. The answer is to deal with the aphids, or to band the trunk so the ants cannot reach them, rather than to attack the ants.

Ants cause direct trouble in two places. Nesting in the dry compost of a container leaves roots in air pockets and the plant wilts, which a thorough soaking or a repot fixes. And nesting under paving undermines slabs and heaps fine soil into a lawn, which is a hard-landscaping problem rather than a plant one.

Set against that, they aerate soil, disperse seeds, and take large numbers of pest eggs and small caterpillars.

What to do about it

Leave earwigs alone everywhere except on show blooms, and trap and relocate them there.

Put an earwig shelter in the apple tree rather than trying to remove them from it.

When ants appear on a plant, look above them for the aphids and deal with those.

Grease band a fruit tree trunk to keep ants off the aphids in it.

Soak a pot that ants have nested in, or repot it.

Sweep out nests in paving rather than poisoning them.

Keep ant powder out of the borders.

What it gets mistaken for

Slugs and snails leave slime trails and rasp holes in foliage rather than petals.

Caterpillars leave dry pellets of frass and eat leaves.

Capsid bugs distort and perforate the newest leaves and are long gone by the time the damage shows.

Bird damage on flowers tears petals off rather than eating holes through them, and it happens in daylight.

Wasps eating ripe fruit make open craters, and the earwigs found inside those craters afterwards usually get the blame for a hole they did not make.