Apple sawfly
Apple sawfly larvae can feed on apple fruitlets in late spring to early summer, affected fruits usually drop off in June. This should not be confused with 'maggoty' apples in late summer which are due to codling moth.
Quick facts
Latin name Hoplocampa testudinea
Plants affected Apple fruits
Main symptoms Holes in fruitlets that fall from the tree in early summer; elongate ribbon scars on mature fruits
Caused by Caterpillar-like larvae of a sawfly
Timing Late April-June
What is apple sawfly?
Sawflies are a group of insects suborder (Symphyta) of the Hymenoptera (bees, ants and wasps). There are about 500 species of
The caterpillar-like larvae of
Symptoms
Signs of apple sawfly include:
- In late May and June, affected fruitlets have obvious holes with the larva’s blackish-brown excrement pellets spilling out
- Each larva can feed on several fruit
- Affected fruitlets usually drop off the tree as part of the June drop (when apple trees shed excess fruits), this loss of fruits is often light and so should be tolerated
- Fruitlets that suffered only initial feeding damage by a sawfly larva can stay on the tree and develop as fruits. These fruits are usually misshapen and have a long ribbon-like scar about 4mm wide, often starting at the eye end of the fruit and extending around the circumference. The fruit is usually still edible when this occurs
Management
The presence of apple sawfly can usually be tolerated and in years when there has been a heavy fruit set, a bit of fruit thinning caused by apple sawfly can be beneficial.
Some cultivars, such as ‘Worcester Pearmain’, ‘Charles Ross’, ‘James Grieve’ and ‘Ellison’s Orange’, seem to be particularly susceptible to apple sawfly. Apart from ‘Early Victoria’ and ‘Edward VII’, cooking apples are rarely affected.Check apples once fruit has begun to set so action can be taken before a damaging population has developed. When choosing control options you can minimise harm to non-target animals by using the methods in the non-pesticide section below. Pesticide treatments are likely to kill natural enemies and are only likely to be successful if the entire plant can be reached.
Non-pesticide
- Where possible tolerate populations of sawfly, affect on copping is usually light and can be beneficial to a healthy crop
- Encourage predators and other natural enemies of sawfly in the garden, such as birds and ground beetles
- Pick off damaged fruitlets when they are seen to prevent the larvae moving to other fruitlets or going into the soil to pupate.
Pesticides
The RHS recommends that you don't use pesticides. Most pesticides (including organic types) reduce biodiversity, including natural enemies, impact soil health and have wider adverse environmental effects.Where you cannot tolerate apple sawfly, manage them using the information above as your first course of action.
Pesticide treatments are likely to kill natural enemies and so reduce the likelihood of natural control and can lead to resurgence of the target animal.
The pesticides listed are legally available in the UK. This information is provided to avoid misuse of legal products and the use of unauthorised and untested products, which potentially has more serious consequences for the environment and wildlife than when products are used legally.
Shorter persistence products (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife.
Homemade products are not recommended as they are unregulated and usually untested. Be aware that products such as Neem are not registered for use in the UK and we cannot advise they are used.
Plants in flower must not be sprayed due to the danger to bees and other pollinating insects
- Control with pesticides of apple sawfly is usually unnecessary
- Organic contact insecticides containing natural pyrethrum (e.g. Bug Clear Ultra 2, Neudorff Bug Free Bug and Larvae Killer). Several applications of this short persistence products may be necessary to give good control
- Further information about the use of pesticides available for management of sawfly is available in the pesticides for gardeners leaflet.
Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener
Download
Pesticides for gardeners (downloads pdf document outlining pesticides available to home gardeners)Biology
Adult apple sawflies are active in late April-May and can be seen visiting the open blossom. They are 4-5 mm long, the head and thorax are blackish brown and the abdomen is brown.
Eggs are laid at the base of the flowers. After petal fall, the eggs hatch and the caterpillar-like larvae start feeding. Initially the larvae tunnel beneath the skin of the developing fruitlets. Later they bore into the core of the fruitlets, and this feeding damage causes affected fruit to drop in early summer. If the larva dies before reaching the core, the fruit can survive and develops but has a ribbon-like scar on the skin where the early feeding took place.
When fully fed, the larva is about 10mm long and has a brown head and white body. Each larva can damage 3-5 fruitlets before it completes its feeding and goes into the soil, where it overwinters as a non-feeding larva and pupates in the following spring.
See also...
Big Garden Sawfly Survey (External link)
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