Ask Mr. Smarty Plants

"Evergreen" is a pretty broad category, but we are betting that in your part of the country, USDA Hardiness Zone 6b, most of your evergreens would fit into the Conifer category. When we searched our Native Plant Database on "trees" and New York we found these conifer families native to New York:

Pinaceae (pine) - includes pines, spruce, and fir

Cupressaceae (cypress) - includes arborvitae, juniper, cedar and bald cypress (which is not evergreen)

Taxaceae (yew)

There are also 3 members of the Ilex (holly) genus that are evergreen, but they don't share the pest problems that the conifers do.

So, you see, we really don't know which evergreens you are asking about, but we do know that we have had inquiries from various parts of the country on diseases affecting conifers, mostly junipers, and Blue Spruce in the Western United States. Most of these, if not all, seem to be related to various species of spider mites. Rather than repeat a lot of material, we are going to link you to some previous Mr. Smarty Plants' answers, all of which have links to sites on the insects involved. We would also suggest you visit the website of the Department of Environmental Conservation, Division of Lands and Forest, New York. Since there are 4 counties on Long Island, and several Baldwins in New York, we are going to take a guess and refer you to the Cornell Cooperative Extension Office for Suffolk County. Even if that is not your county, they will know what you are talking about and hopefully will provide you with some information.

Previous answers on similar questions from Mr. Smarty Plants:

Juniper mites May 27, 2011

Evergreens in New York, October 25, 2008

Arborvitae December 16, 2010

Junipers August 1, 2010