The Balsam Twig Aphid
The balsam twig aphid (Mindarus abietinus Koch) (BTA) is a small, pale green aphid that feeds on fir trees in the spring. BTA feeding on the new growth of Fraser fir often results in permanently curled needles.
The link address is: http://www.ces.ncsu.edu/nreos/forest/xmas/CTN019.html