This is one of those times where I was curious about what this could possibly be, proceeded to research, then wished I hadn’t; a little too much info. But, nature does take care of the smallest of details.
Female pine spittlebugs lay their eggs in late summer at the base of needle buds. Eggs winter and hatch the following spring when young insects emerge to feed on the sap. As they feed, they form spittle. Often these foamy, frothy bubbles of spittle can be seen on the twigs and near the base of individual needles or needle clusters. The froth serves a number of purposes. It hides the nymph from the view of predators and parasites, it insulates against heat and cold, thus providing thermal control and also moisture control.