What Insecticides Kill Sawfly Larvae
The pear fruit sawfly (Hopolcampa brevis) originated from Europe and can be found in most areas of the U.S., This insect is a garden pest that’s active during the spring months. The larva is also known as the pear slug or the cherry slug but though it resembles a slug it’s not a true slug. The larvae burrow inside of the pear fruitless during the early spring months where feeding begins.
Pear Fruit Sawfly Biology
The adult population of pear fruit sawflies is mostly females, the females are glossy black wasps about 1/5 inch (5 mm) long. The female wasp reproduces without mating. During the spring months when the sawfly is most active, the female lays a single egg inside of the epidermis of up to about 40 pears per flower. The egg is tan to oval 1 mm long and appears as a small blister on the leaf, In about one to two weeks the larva hatches and tunnels into the pear fruitlet and begins feeding, what I found to be really amazing is that one larva can in a period of 20 to 34 days enter and exit multiple fruits.
Signs of the Pear Fruit Sawfly
Look for these signs on fruits.
- Premature fruit drop
- Blemish skin
- Black decay & wet frass
- Fruits are swollen and deformed
- Round hole can be found near the calyx
How to Control the Pear Fruit Sawfly
Cultural Control: During the months of August and September monitor your tree for the slug-like worm larvae, this is when a large population starts to build up. Individual larvae can be washed off with a strong stream of water or picked off by hand. Deciding where to treat insects depends on the previous year’s damage. The pear slug feeds by eating the tissues between the leaf veins. This feeding pattern is known as skeletonization or leaf skeletonizer, the plant leaves take on an appearance that looks like lace.
Note: There are 2 generations of pear sawfly each year, the second generation larvae do the majority of the damage. The pear fruit sawfly overwinters as a pupa in a cacoon that’s two to three inches deep inside of the soil. During late April and May the adult emerges. The female inserts her eggs into the leaf tissue, and the eggs hatch in about two weeks. The larvae soon start to feed on the upper leaf surface. After 3 to 4 weeks the larvae drop to the soil to pupate. The second generation of adults emerge in July. The larvae of this generation feed in August and September, and most of the larvae from this generation drop to the ground to overwinter.
Controlling Pear Fruit Sawfly with Insecticides
There are many insecticides that can be used to bring control but before applying insecticides read and follow the manufacturer’s directions for the best results.
- Malathion
- Permethrin
- Carbaryl
- Insecticidal soap
- Spinosad
- Neem oil
- Bifenthrin
These listed insecticides will give good results
Note: Make sure that kids and pets remain out of areas that are treated with insecticides.
The final word on pear fruit sawfly control
The pear fruit sawfly is a garden insect pest that can do a lot of damage if control measures are not put in place, Understanding the insect’s biology, timing and the right treatment will bring control.
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About the author
Norman loves being in the garden, both at home and for his job....
he is 'Natures Little helper' being outdoors, growing his vegetables and flowers from an early age.
Now having spent over 22 years in the profession he want to give some of his knowledge to others...
his vast array of hints and tips you will find scattered over this site will help you no end growing plants in your garden.
Norman, thank you for sharing this insightful piece on pear fruit sawfly control. I have to admit, I didn’t know much about this pest before reading your post, and it’s fascinating to learn about its life cycle and the damage it can cause.
I’m particularly impressed with the cultural control methods you’ve mentioned. Using a strong stream of water or hand-picking the larvae during August and September seems like a practical approach. It’s great to have eco-friendly options like this.
I’ve found your post to be incredibly informative and helpful. I’ll definitely keep these control measures in mind should I encounter pear fruit sawflies in my garden.
Thank you so much for your kind words, I am so happy to help.