Yes, if you had Gypsy Moths in the last two years it's highly likely you will have them again this year, but with even greater damage. Gypsy Moths come back stronger the year after a drought, and the 2015/2016 summers were very dry.
Yes, if you're neighbors had gypsy moths you're highly likely to get them in your yard as well.
Gypsy moth larvae prefer oak trees, but may feed on many species of trees and shrubs, both hardwood and conifer. In the eastern US, the gypsy moth prefers oaks, aspen, apple, sweetgum, speckled alder, basswood, gray, paper birch, poplar, willow, and hawthorns, amongst other species. The gypsy moth avoids ash trees, tulip-tree, cucumber tree, American sycamore, butternut, black walnut, catalpa, flowering dogwood, balsam fir, cedar, American holly, and mountain laurel and rhododendron shrubs, but will feed on these in late instars when densities are extremely high. Older larvae feed on several species of softwood that younger larvae avoid, including cottonwood, hemlock, Atlantic white cypress, and pine and spruce species native to the east.
Gypsy moth egg masses are typically laid on branches and trunks of trees, but may be found in any sheltered location, including rocks, foliage and vehicles. The egg masses are a buff yellow-brown color, likened to a manila folder, but may bleach out over the winter months.
Mechanical methods include physically scraping the distinctive beige egg masses which are deposited by female moths (during the breeding period usually during the first few weeks of July) off of the trunks and other large main branches of the susceptible trees.The scraping should be done placing the eggs in a container typically a metal food can or bucket containing a small amount of kerosene or other light oil.Simply scraping them off and onto the ground is not effective as they will just hatch anyway and crawl back up the tree.
Preventative barriers include cheesecloth, burlap and other fabrics which are wrapped around the trunk of the tree. These barriers interfere with insects ability to move up and down the tree which is important for their protection from predators and their ability to feed. Other barriers can be used including pastes or grease which are painted or brushed onto the tree trunk.
Organic sprays like Spinosid are naturally derived compounds that are toxic to the caterpillars when they are timed and applied properly. Spinosids are topically sprayed onto the surface of the leaves. They are not chemicals and do not remain in the eco system
Chemical sprays are products used by farmers, foresters and the landscaping and nursery communities. They have been in use for decades and have vast data experiences; as such they are the most commonly used and least expensive option. That having been said; they need to be applied with care and by professionals or individuals who follow all directions and precautions.
Chemical systemics are similar to vaccinations for trees. They are intergrated into the metabolism of the tree, translocating an active ingredient to the leaves. The caterpillars feed on the leaves and become unable to digest their meal. This product has a shelf life and remains in the tree for about 90 days.These are products best utilized by professional licensed aplicators.
Another option is a biologic agent known as BT. This is a bacteria which has been developed to cause the insect to stop feeding after interfering with its ability to process food. When the populations of caterpillars decline Bt does as well and remains dormant until the next outbreak is large enough to cause the populations to collapse. Unfortunately great swarths of damage occur in untreated areas before this occurs naturally.
Dormant oil in also a choice. Dormant oil creates a seal which suffocates the eggs living in the egg mass This method has to be timed properly, is time consuming and almost guarantees that many masses that are hidden or are not manually accessible will be missed.
There are additional options but they are not feasible for individuals who do not have access to something like an entomological insect rearing labs. In well funded large scale applications private and government operations have raised predator insects that attack and kill or consume pests . These methods are still being tested and have shown promising results.
There are reasons why you do not want your trees defoliated other than the obvious visual ones. Your trees are dynamic living organisms. Like most living things their quality of life is based on the their ability to manufacture food. This is done by leaves generating sugars which the trees metabolize through seasonal periods of growth between May and October utilizing photosynthesis. If the leaves are damaged, eaten or in some other way compromised, the trees will be weakened. After several consecutive seasons of this the trees can be killed.
The toxicity of Btk has been researched in laboratory studies with animals and by monitoring people for more than 25 years. Btk is low in toxicity for humans and other mammals. It is unlikely that indirect exposure to Btk will result in adverse health effects in people considering the widespread use of Btk in food crops and in insect control.
After a thorough review of the toxicity of Btk products, including both active and inert ingredients, the US EPA, Health Canada, the World Health Organization, and many other groups categorize Bacillus thuringiensis as a least toxic method of pest control.