Eggs found under sumac tree leaves

I've noticed that my three year old sumac tree had some wilting yellow leaves, and some leaves that had curled. Previously the sumac has always been very healthy and hardy, so I was surprised and went in for a closer look.

The attached pictures show what I found, and what I am hoping you can help me to identify. There is definitely some sort of pest infestation, with brown/orange colored eggs. I also noticed some tiny flies with long wings flat to their backs, but I'm not sure if they are related to all of the eggs.

I've googled quite a bit this evening, but haven't found anything that really matches what I saw. Hope someone can help!

Those are aphids. There are many different types, so I don't know which one. The winged ones are just another life stage of the smaller ones. Insecticidal soap should help.

I also have aphids in sumacs, but they are in galls attached to the underside of the fronds. Apparently they are Melaphis rhois. Wondering what I should do about them.

http://lh6.ggpht.com/_giU30s4iu9U/SK...0/IMG_0969.jpg