I need help with fruit tree caterpillar damage. In very short order, my pear tree is completely defoliated, and my plums and apple are seriously set back. The culprits are 3/4″ light green worms. Any idea what they are and what I should do now?
Jonathan Foster, Special Project Assistant
I’m very sorry to hear about your pest issue.
I reached out to one of our Extension entomologists, Mr. Charlie Armstrong, for positive identification on your photo. What’s shown in your photo are sawfly larvae, a common pest on fruit trees. He believed it’s possible it may actually be pear sawfly you’re dealing with (there are, as you’ll read, numerous types). In instances where the damage is not widespread, the pests can often be hand picked and disposed of, or removed with a strong jet of water, without lasting problems for the tree. You’ll have to decide the level you can tolerate, but if the trees are becoming badly defoliated (as you mention and show), you will need to consider chemical intervention. Spinosad is an effective pesticide, per Charlie and the resources linked above, and it can be purchased at garden centers and online. As always with pesticides, please read the instructions carefully and follow them diligently, to achieve effective results while protecting yourself and the environment.