Sasha CampbellSawflies belong to the same insect order (Hymenoptera) as bees, ants, and wasps. They are named for the saw-like ovipositor the female uses to pierce plants and lay eggs [1].
The adult sawfly resembles a wasp, but unlike wasps, it does not sting people.
Moreover, different species of sawflies feed on different plants. Examples include the European pine sawfly, rose sawfly, elm sawfly, and birch sawfly, among others.
These insects go through four distinct stages in their life cycle: egg, larva, pupa, and adult. However, the larvae are the main culprits behind most plant damage, so you must get rid of them quickly.
Sawfly Larvae Identification
Sawfly larvae resemble small worms, and gardeners often mistake them for caterpillars. However, they must be correctly identified, as some treatments used against caterpillars, such as Bt, are ineffective against them.
Help with identification can be found at Wildlife Insight.
Signs of a Sawfly Infestation
- Skeletonized leaves.
- Defoliated branches.
- Clusters of larvae on leaves or needles.
- Chewed leaf edges.
- Brown or dying foliage on heavily infested plants.
How to Get Rid of Sawflies Naturally
Depending on the number of adult sawflies and their larvae, getting rid of them can be complex or straightforward.
The following are 13 natural sawfly control methods you can try:
1. Pick Them Off
Put on a pair of gloves and pick off the larvae and/or eggs from the leaves or needles.
Next, squish them. You can also drop them into insecticidal soap to kill them.
2. Birds
Once mature, the larvae drop to the ground to pupate in the soil. Disturbing the soil or leaf litter can expose pupae to birds and other predators.
Placing a feeder by the affected plants can also attract birds.
Once they have something to feed on, the birds will keep coming back, and they will also notice any sawfly pupae on the ground.
3. Soap Spray
Since the larvae are soft-bodied, a homemade spray made with 4 tablespoons of pure liquid Castile soap and 1 gallon of water will help remove them from the plants.
The soap damages the larvae’s protective outer coating, causing dehydration and death.
4. Use the Water Hose
Spraying plants with a strong blast of water will dislodge the larvae. However, be careful not to use too strong a spray, or you might damage the plants.
5. Diatomaceous Earth
To control pine sawfly larvae and other sawflies, apply diatomaceous earth to the affected plants by sprinkling it on the foliage.
Diatomaceous earth also works to keep snails off plants like gooseberries and rose bushes.
Food-grade DE is considered low in toxicity to humans and pets when used correctly and can help reduce sawfly larvae populations naturally.
6. Kaolin Clay
Applying kaolin clay to plants will also deter sawflies and other insect pests. It forms a protective film on plants that discourages feeding and egg-laying by many insect pests.
7. Neem Oil
Neem oil is an all-natural insecticide made from the neem tree. It contains azadirachtin, a very potent substance that kills or repels many garden pests.
Combine four teaspoons of neem oil with a gallon of water and a small amount of liquid soap. Spray this homemade sawfly killer on leaves and other affected areas.
8. AzaGuard
This botanical insecticide works against several insect pests, including sawflies. Its active ingredient is also azadirachtin.
Moreover, AzaGuard is commonly used in organic gardening programs.
9. Vacuuming
This DIY method can also help control sawflies.
If the vacuum has strong enough suction and you’re quick enough, you may even be able to capture adults before they fly away.
Use a vacuum to suck up the larvae, eggs, and any adults you see. Next, dispose of the critters in soapy water right away.
10. Attract Predators
Sawflies have many natural predators. Doing some research will show which species are native to your area and give tips for attracting them.
Natural enemies of sawflies include birds, frogs, lizards, parasitic wasps, and predatory beetles.
Try attracting these natural predators to your garden.
11. Spinosad
Spinosad can control pear slugs, caterpillars, and other garden pests. It affects the pests’ nervous system, causing paralysis and death within a few days.
However, the only drawback of this sawfly treatment is that it may not be effective against eggs. The pests’ soft bodies need to absorb it for it to work, and the eggs have hard shells.
Avoid spraying spinosad on flowering plants when bees are active, as it can harm pollinators.
12. Beneficial Nematodes
The nematodes will enter the bodies of larvae and pupae, becoming parasites that eventually kill them.
Place beneficial nematodes in the soil around plants. Beneficial nematodes are most effective against sawfly pupae and soil-dwelling larval stages.
13. Horticultural Oil
This oil is also an excellent natural remedy for rose slugs. When applied, horticultural oil coats eggs and larvae, blocking their ability to breathe and eventually killing them.
This method is one of the most effective ways to kill the eggs before they hatch, thereby saving the plant from further damage.
What Do Sawflies Eat?
The larvae feed on the leaves and needles of trees and shrubs, causing most of the visible plant damage. However, some feed exclusively on roses, hibiscus, raspberries, and gooseberries.
You may also find sawflies on barberries, plums, bottlebrushes, creeping Jenny, dogwoods, willow trees, mallows, and azaleas. Many sawfly larvae feed in clusters, especially in their early stages.
Damage to Crops
Damage from plant-feeding larvae can vary.
It can be slight or severe. This depends on how many larvae there are and the health of the plants they eat.
Sawfly damage to leaves or needles can take the form of holes in leaves, leaves eaten down to the veins, galls on the leaf surface, or rolled-up leaves.
Healthy, mature plants are less susceptible to this kind of damage. However, young or weak plants will show more damage.
Takeaway
Whether you call them sawfly worms, rose slugs, or pear slugs, sawfly larvae can be a problem in your garden. While they won’t harm people or animals, they can cause significant damage to some plants.
Getting rid of an infestation is the best course of action for a healthy garden and/or orchard.
Using natural pest control methods can reduce sawfly damage. These methods are gentler on the garden ecosystem than many conventional insecticides.
Thank you so much! This is the most comprehensive article I have seen for dealing with these ornery pests! They devastate my pear tree every year and as an organic gardener I have been struggling to get rid of them. Thanks for the abundance of new “tools”.