Caterpillars bugging us

BUT DEM Says Conditions Expected to Improve Next Month

The Rhode Island Department of Environmental Management (DEM) is advising homeowners that high concentrations of caterpillars observed statewide may cause short-term defoliation of trees over the next few weeks.

Typical damage, most commonly to oaks and other hardwood species, includes small holes in leaves or leaves that have been chewed down to the veins. 

These conditions are temporary and should not cause long-term damage to otherwise healthy trees. 

By the end of next month, impacted trees should start to re-foliate with the proper care. 

Watering trees during times of drought is advised during recovery from defoliation. Applying fertilizer is not recommended for trees that have been defoliated.


Homeowners may opt to apply insecticides to control caterpillar populations on their property. 

Products containing the active ingredient "Btk" are recommended and widely available at retail outlets. 

Many tree care specialists are also licensed in pesticide application. 

At this time, the state has no plans to apply pesticide to control caterpillar populations, as numbers will eventually decline naturally. 

DEM does not advocate for the widespread use of pesticide in forested areas given its adverse impact to other beneficial insects, such as bees and butterflies.

For more tips on caring for trees, visit www.dem.ri.gov. Follow DEM on Twitter (@RhodeIslandDEM) or Facebook at www.facebook.com/RhodeIslandDEM for timely updates.