That looks like pine leaf adelgid. To make sure, you can take a sample to your local Penn State Extension (here is a link). Spraying horticultural oil on adelgids will suffocate them, but you will have to persist because they come back from untreated treas. Here is a link to a publication on controlling pine leaf adelgid. They mention chemical controls as well, but it can become expensive to use chemicals since you have to treat the trees every time a new batch of adelgids arrives. They also mention beetles as a biological control,