A few winter moth eggs have started to turn blue in Franklin, MA, and one hatched caterpillar was found there today. In southern RI, a few blue eggs have been seen on trees with 1000s of eggs. The more eggs available for monitoring, the more likely we are to find really early hatching eggs.
Thursday and Friday, March 17 & 18, should be relatively warm and then it’s predicted to cool down for 4 days. I think once it warms up again, next Wednesday March 23, we will start seeing egg hatch everywhere except for very cool areas along the coast. Spring always lags behind in Little Compton and Tiverton and along the coast. Eggs are being monitored in Little Compton, so I will be able to provide information about when eggs hatch in cooler locations.
Of course, weather predictions can change, but I think March 23 could be a good day to apply an insecticide to apples, pears, and blueberries in most locations infested with winter moths. I’ll send out additional information if things change.
Insecticide choices from March 4th update:
Winter moth caterpillars are pretty easy to kill, provided they are not inside closed buds. Insecticide choices for when caterpillars start to hatch for fruit growers include, but are not limited to, spinosad, Imidan, Sevin, Malathion and synthetic pyrethroids such as Asana. Spinosad products are Delegate, mostly for commercial growers, Entrust for organic growers, and Captain Jack’s Deadbug Brew is formulated for small-scale growing. Adding a dormant oil may be useful for the first spray of any of the listed insecticides.