The Rhode Island Department of Environmental Management (DEM) is advising homeowners that it does not anticipate widespread defoliation of trees by gypsy moth caterpillars in Rhode Island this year, as occurred in 2016 and 2017. There will still be some localized areas, however, where tree defoliation may be severe.
Surveys conducted last fall by DEM’s Division of Forest Environment showed a marked decline in the number and size of gypsy moth egg masses in the environment; thus, there will be fewer caterpillars hatching this spring. Areas expected to be hit hardest include central Providence County and Washington County, although all forested lands, parks, and urban green spaces are still somewhat at risk.
Spring rains last year promoted the emergence and spread of the Entomophaga maimaigafungus, a pathogen deadly to the gypsy moth. This resulted in significant caterpillar mortality. Spring rains this year will once again release Entomophaga, likely causing a total collapse of the caterpillar population. Unfortunately, some trees will be defoliated before this happens. A report on the status of the current outbreak can be found by clicking here.
Homeowners may opt to apply insecticides to control caterpillars on their property, minimizing damage to their trees. Products containing the active ingredient “Btk” are recommended and widely available at retail outlets. Many tree care specialists are licensed in pesticide application, and may be contracted to do so. Click here for information on contracting with a tree care specialist providing this service. DEM does not advocate for the widespread use of pesticides in forested areas because they also harm beneficial insects, such as bees and butterflies. DEM has no plans to apply pesticides this year.