Emailed Apple Pest Message – March 21, 2012

I just got back from Wakefield RI and found many hatched winter moth caterpillars on a tree where the owner had set up tree bands last fall. The eggs on the north side of the tree were still orange and not hatching. (Eggs turn blue soon before hatching.) On the south side of the tree, nearly half the eggs had turned blue, and several of the blue eggs were empty and larvae were found on the trunk. I’ve attached a picture of eggs on the tree bark, about half of which are orange and the other half are blue. Many of the blue eggs show emergence holes where the larvae chewed their way out of eggs. I didn’t see all the caterpillars when I took the picture (bad eyes), but there are 8 newly hatched larvae in the picture. They are dark green with black heads.

The tree with winter moth eggs hatching is only about 2 miles from Narragansett Beach, so not one of our warmer locations in Rhode Island. I think that eggs are probably hatching in Bristol and Portsmouth as well warmer locations in the state. Little Compton may be a few days behind, but I was over there on Friday and surprised at how similar plant stages were to the ‘main land’.

Today I looked at some McIntosh apple trees and they are still not yet at the ‘green tip’ stage, but probably will be tomorrow.

So if you want to protect buds from winter moth larvae I suggest you spray very soon. Most insecticides control winter moth larvae very well. As I’ve said before, most landscape trees don’t need to be sprayed so early and can wait for the buds to open.