April 16, 2015
Winter moth egg watchers in Warwick saw several blue winter moth eggs this morning. In Kingston today I found one blue egg. Winter moth eggs turn blue a couple of days before hatching. I think right after tomorrow’s rain is a good time to apply an insecticide to control caterpillars. In some colder areas, such as Little Compton, it is probably better to wait a few more days. The forecast for Saturday is 70, so I expect many eggs will hatch then. The plan is to apply the insecticide right before eggs hatch so caterpillars are killed before they enter buds and begin feeding.
Looking at the Weather Channel growing degree day calculator for April 15:
4/15/15 Bristol 120 GDD 02809
4/15/15 Cumberland 102 GDD 02864
4/15/15 Greenville 102 GDD 02828
4/15/15 Kingston 108 GDD 02881
4/15/15 Little Compton 86 GDD 02837
4/15/15 Middletown 86 GDD 02842
4/15/15 North Kingstown 108 GDD 02852
4/15/15 Warwick 120 GDD 02889
4/19/15 Westerly 90 GDD 02891
Adding a dormant oil to your insecticide spray may be beneficial. Be sure to spray all branch and trunk surfaces.