What the heck is a pear slug?? These are not your typical, large ground sliding, slimy slugs. Despite their name, Pear Slugs are actually an insect. They are the larva of the Sawfly and are also known as cherry slugs.
These are tiny little creatures that pupate and become very similar looking to a regular fly. In Latin they are known as Caliroa cerasi.
Pear Slugs aka Cherry Slugs have a maximum size of ½”. These little guys are tiny but very destructive. Pear slugs prefer your pear trees and cherry trees but will also eat other similar varieties too if they are available. Among the most commonly affected are the plum, hawthorn, apricot and cotoneaster, as well as apple and quince.
Life Cycle
It’s important to take eradication action as soon as you see the problem. They have two hatching cycles per season and can be very detrimental to a tree.
They will eat the leaves of the current years growth but will also over-winter in the bark and soil around the tree and be back in force next year. After they’ve safely made it though winter, they attack the tree again in greater numbers than the year before.
The second generation is more destructive and active than the first. If you live in a warm, temperate climate you may face 3 generations per season.
Pear Slug Damage
At first your leaves will appear spotty and brown, then very quickly will turn papery and crisp. Then they will eventually shrivel and fall prematurely. If the infestation is really severe you will actually be able to hear the slugs eating the tree. I have witnessed that first hand.
If you see them on your tree the only thing that you probably want to know is how to get rid of them right away.
Remedy
The quickest and very effective remedy to this pest is to use a solution of dish soap and water in a spray bottle or hose end sprayer if it’s a large tree. The goal is to completely saturate your tree with the solution.
It’s important to completely, 100% saturate your tree. The pear slugs are very sensitive to dish detergent and will only die if the dish soap comes in direct contact with them. It dries them out, they shrivel up and die promptly. The dish soap cuts through their outer protective layers of slime and they quickly dehydrate.
If your tree is small then a squirt bottle or small air pressure sprayer is fine but if your tree is large then a hose-end sprayer or a backpack sprayer will be required.
Remember that complete saturation is required. Over-spray and dripping onto the soil is fine, it will allow the excess dripping of the solution to come into contact with the ground dwelling larva waiting for their turn which are currently invisible to us. Spray the ground directly as well if there is any vegetation there.
Keeping the ground area under the tree clean and without ivy or other plants underneath. It’s a big part of the remedy as well, if you have thick plants such as ivy surrounding the base of the tree, I recommend removing this as this is perfect sheltered breeding ground for them.
The pear slugs are protected from the elements and are over-wintering in there to breed again in the spring. The ground plants are helping to make the problem much worse and will make it more difficult to combat the problem.
If you want a traditional pesticide other than dish soap, then look for ones that contain Carbaryl or the product called “Sevin” as shown below.