Good article on winter moth caterpillars in The Bedford Citizen:

An earlier article discussed the appalling extent of the danger posed by the winter moth, with its voracious appetite for our native northeastern trees and shrubs—especially red maples and oaks—and its ability to “balloon,” or float, from treetop to treetop,  as well as their appearance and behavior. This addresses what to do about them in greater detail.

The main topics:

• When to treat
• Do it yourself or hire a professional?
• Details of treatment options (chemicals)

Winter moth caterpillars can do a lot of damage.  We’ve had our trees sprayed by Boston Tree Preservation the past several years and will have them do so again this spring.  (I tried spraying some shrubs and young trees myself but getting up high on mature trees was a non-starter.)