Pear and cherry slug: identify, prevent, control

Updated October 2026

Two generations a year in southern Australia: a smaller one peaking around November and a much larger one from mid to late summer.

Pear and cherry slugs are not slugs at all but the larvae of a small black sawfly. They feed on the upper surface of leaves on pears, cherries, plums, quinces and hawthorns, leaving a lacy brown skeleton. They rarely kill a tree, but a bad late summer attack can strip most of the leaves and weaken next season's crop.

Caliroa cerasi

How to identify it

• Look on the upper side of the leaves for small, glossy, dark olive to black larvae about 5 to 10 mm long that are fatter at the head end, like a tiny leech or tadpole.
• The larvae are covered in a slimy coating, which is why they look like slugs, and they turn yellowish just before they drop to the soil to pupate.
• Feeding scrapes away the upper leaf surface between the veins, leaving a see-through, window-like patch that soon turns brown.
• In a heavy attack whole trees turn brown in late summer, as if scorched, and leaves fall early.
• The adult is a small, shiny black sawfly about 5 mm long that cuts tiny slits in leaves to lay its eggs.

What it is often confused with

When and where it is worst

This European sawfly is widespread across southern Australia, including New South Wales, the ACT, Victoria, Tasmania, South Australia and the south-west of Western Australia. It is a common sight in cool and temperate gardens from Hobart and Melbourne to Canberra, Adelaide and the tablelands. Pears and cherries are the hosts listed on our site, and it also attacks plums, quinces, apples, hawthorns and ornamental cherries and pears.

The insects spend winter as pupae in the soil under host trees. Adults emerge in spring and the first generation of larvae feeds from about October, peaking around November. These larvae drop to the soil, pupate, and a second, much larger generation appears from mid to late summer, often after cherries have been picked, and it can strip trees by February and March.

Plants it attacks

These plants in our library list it as a problem to watch for.

How to prevent it

• Start checking the upper surface of leaves from October, especially on lower branches you can easily see.
• Act on the first, smaller generation in spring, because that is the key to preventing the big summer generation.
• Keep flowering plants nearby to encourage hoverflies, lacewings, paper wasps and birds that eat the larvae.
• After harvest keep watching cherries, which are often hit hard once the fruit is off.
• A thick layer of mulch under the tree may reduce the number of adults emerging from the soil in spring.

Organic control, step by step

• On small trees, pick the larvae off by hand or hose them off the leaves with a strong jet of water.
• Dust the larvae lightly with fine wood ash, hydrated lime, talc or flour on a dry day; the powder sticks to their slimy coating and dries them out.
• If numbers are high, spray spinosad, an organic-certified insecticide, where the label lists pear and cherry slug, covering the upper leaf surface.
• Repeat checks two weeks later, because eggs hatch over several weeks.

Conventional control

• Spinosad is the most widely used home garden insecticide for pear and cherry slug and is suitable for organic gardens; apply when larvae are young.
• Natural pyrethrins can also be used where the label lists the pest and crop; spray in the evening to protect bees.
• Read the label, check the crop is listed and keep to the withholding period before you pick fruit.

Frequently asked questions

Related problems

Sources: NSW DPI via Tree Fruit, Pear and cherry slug; Yates Australia, Pear and cherry slug; Sustainable Gardening Australia, Pear and cherry slug. Identification and control follow these sources. Always read the product label before use.