Controlling Raspberry Fruitworms: Preventing Fruitworm Damage On Raspberries

Controlling Raspberry Fruitworms: Preventing Fruitworm Damage On Raspberries

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By: Kristi Waterworth

Raspberry patches give home gardeners easy access to the tasty fruit these canes produce, making berry-picking a fun experience for the whole family. Like other berries though, raspberry fruits are frequently invaded by worms that can ruin a harvest. These raspberry worms are the larvae of a tiny beetle, known as the raspberry beetle (Byturus unicolor).

The raspberry fruitworm beetle reaches up to about 1/5 inch (5 mm.) long, its reddish brown body is covered in tiny, short hairs. Adults feed voraciously on leaves of raspberry canes, favoring the newest canes and leaves, but may spread further when populations are high. Mating takes place on or near raspberry flowers, where eggs are deposited.

Fruitworm Damage on Raspberries

Adult raspberry fruitworm beetles appear from mid April to mid May, eating the surface tissues from raspberry leaves or skeletonizing them entirely. They may feed on opening flower buds when they appear, if numbers are large– even whole bud clusters are sometimes consumed. However, the damage from the adult beetle is usually insignificant to the plant as a whole.

Raspberry worms, on the other hand, can cause serious economic damage. When these tiny worms hatch they find themselves inside or up against individual fruit caps. The larvae burrow into the raspberry receptacles, sometimes causing fruits to dry up or drop prematurely. Infestation ultimately results in the downgrading of commercial harvests when raspberry worms are found among the fruit.

Controlling Raspberry Fruitworms

If you pay close attention to your raspberries throughout the spring, you may be able to catch the tiny raspberry fruitworm beetles shortly after emergence, but before they’ve begun to lay eggs. Handpicking is possible, even though these pests are small, if you are determined. Dropping them into a bucket of soapy water will kill them quickly.

Killing raspberry fruitworms naturally is a goal of most gardeners, who prefer not to add pesticides to home-grown fruits. Spinosad is a microbial pesticide allowed in organic gardens and considered totally harmless to humans, but you must restrict the use of this chemical to evenings since it is dangerous to bees while wet. Spray raspberry canes with active beetle populations as soon as they are noticed or wait until flower buds swell to target raspberry worms specifically. A second application after bloom may be required to kill all the worms.

After harvest, raking, or shallowly cultivating the soil around your raspberry canes can break up pupating larvae in the soil. If you keep chickens, this is a great time to let them in the garden to help destroy the tasty beetles.

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Comments (5)


I hate to say it, but it sounds like you might be finding spotted wing drosophila maggots in your fruit. SWD is a new pest. Are they small (smaller than a grain of rice) and white?

I posted a link to the thread I started about SWD a few weeks ago.

Here is a link that might be useful: SWD post


Thank you, fruitgirl, for information.
I live in Washington, near Seattle. From the reading, i see that i got SWD.
I will miss my raspberries if i will not find how to fight fly organically.
I managed to fight currant fly with covering bushes after they finished flowering with a net, but raspberries are not flowering all at the same time, covering can be a problem.

Have you read about usage of used coffee drounds?
I am going to cover soil around my raspberries with coffee ground (thanks to Starbucks) hoping that cofein will kill pupae.

Any thoughts or info on this approach?


If this cures the problem, apply the Sequestrene next year because it is not a permanent solution. The only permanent solution is to increase the acidity of the soil so that iron can more easily be taken up by the raspberry bushes.

If older leaves are most affected, suspect a magnesium deficiency. The long-term solution to a magnesium deficiency is to add Dolomite limestone (readily available at garden centres) to the soil at the dose recommended on the package. Do not exceed the dose because doing so can result in too much calcium which in turn inhibits the roots ability to absorb the magnesium. Dolomite limestone is a slow release product which lasts for a long time in the ground.

A more immediate remedy for magnesium deficiency is to spray the foliage with a solution of water and Epsom Salts. The ratio is 20g of Epsom Salts added to a litre of water and a few drop of washing liquid will help the spray to stay on the leaves. Spray again after a fortnight.


Virus infections initially show yellow leaves / green veins, but they will also begin to show signs of stunted growth and poor cropping over a couple years. If left untreated the bushes will eventually die out.


If your raspberry bushes are significantly younger, yellowing leaves could possibly be caused by cane midge (see here) but there will be additional signs as well. Raspberry Root Rot could also be the problem, but there will be other symptoms. The fruit will either fail to form or be very small, stems will be short and generally look unhealthy.

Root rot is best diagnosed by digging up a plant and examining the roots. They will look unhealthy and, as the name suggests, rotting. They will also have red marks on them where the fungus has initially entered the plant.

General Raspberry Pest Control

Controlling the presence of insects on a raspberry plant is important throughout the growing season. Regular applications of pesticides help prevent beetles and other insects from feeding on the raspberry bush and causing it damage. Follow all directions on the pesticides when spraying chemicals in the garden. Prune the raspberry bush early in the spring to keep it healthy, as unhealthy portions of the plant are more likely to attract damaging insects and beetles.

Watch the video: Steves Allotment - Planting Raspberry Canes 73