Spittlebugs (Clasirptora sp.) can be identified by the froth or "spit" like material that is found on these evergreens as well as many other plants like roses, yarrow and mums. The insects produce the spittle to help protect them from predators and drying out produce the spittle. The insects survive the winter as eggs on the host plants or nearby vegetation. After the eggs hatch in spring, the nymphs feed on a host plant's sap. A clear fluid is produced and surrounds the insect. The nymph adds air bubbles to this fluid thus causing the "spittle" like material.
Generally, most spittlebugs do not cause enough harm to justify any treatment. Where the amount of spittle is undesirable, an insecticide applied under high pressure can be used but hosing them off the plant with water often provides acceptable results.