Pine spittlebug

Distribution

Eastern Canada

Common throughout the range of eastern white pine in Ontario.

Micro-habitat(s)

Twig, Trunk

Damage, symptoms and biology

Pine spittlebug damage is a serious problem, especially in young eastern white pine plantations. The numerous feeding punctures that occur along twigs and branches can produce needle browning at branch tips (flagging), and result in twig and branch mortality. Two or three years of very heavy infestation can result in whole tree mortality. Any age or sized tree can be attacked. During years when the numbers of pine spittlebugs are high, Scots pine in particular can be severely stunted or killed.

The adults are about 8 to 11 mm long and are oval-elongate in shape. They are tan to dark reddish-brown in colour with two narrow, oblique, light bands, usually bordered by darker bands, on each wing cover.

In the spring the young nymphs pierce the bark of the twig and feed on the sap, covering themselves with a frothy mass of spittle. The adults continue to feed through July and August. Females deposit their eggs in dead woody tissue or just under the bark of twigs during the months of July and August. In the northern part of its range, the pine spittlebug spends winter in the egg stage. The nymphs, or young spittlebugs, begin to hatch in May. They feed on the twigs, covering themselves with spittle. As they grow they change locations forming new masses of spittle at each stop. As they approach the adult stage they often move to the trunk of the tree where several of the bugs will occupy a single spittle mass. When the nymphal stage approaches its finale, the now mature nymphs move to the needles and transform to adults. There is one generation a year.

The adults lay their eggs on the bark of the tips of the twigs in July and August. The eggs overwinter, hatching the following spring in May. From May to July the nymphs move periodically inward along the branch towards the main stem. By July they are full grown and have reached the main stem where they congregate and feed together under large spittle masses. After the nymphs change to adults the spittle masses soon dry up and frequently a black sooty mold develops at the feeding sites. The adults continue to feed through July and August.

The pine spittlebug can carry a fungus that invades a tree through the insect’s feeding punctures. This fungus, called Diplodia pini, can weaken the affected tree. Most of the flagging injury attributed to the pine spittlebug is due to the fungus rather than the insect. Controlling the insect however will control the fungal infection. Feeding injury caused by the pine spittlebug also allows sooty mold to invade the tree. This too may cause flagging and eventually the tip of the affected twig will die.

Other information

There is a fungus that infects the nymphs, keeping populations in check. The fungus, coupled with high temperatures during the nymphal stage, can cause heavy mortality of the pine spittlebug.

Main host(s)

Balsam fir, black spruce, blue spruce, Colorado spruce, eastern hemlock, eastern white pine, Engelmann spruce, European larch, hemlocks, jack pine, Jananese larch, larches / tamaracks, mountain hemlock, Norway spruce, pitch pine, red spruce, scots pine, Siberian larch, Sitka spruce, spruces, subalpine larch, tamarack, western hemlock, western larch, white spruce, white spruce