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Spruce budworm

The final map of spruce budworm defoliation isn't done yet, however a preliminary sketch map is available. In Region 2, populations and defoliation levels remain very high in northeastern Itasca, northwestern St Louis and eastern Koochiching Counties. White spruce as well as balsam fir continue to be damaged. Budworm populations and levels of defoliation throughout the rest of the region were at lower levels than last year. Light defoliation continued in scattered white spruce plantations in Itasca County. In Regions 1 and 3, white spruce plantations continue to be targeted by the budworms. Some plantations are beginning to experience topkill. Egg mass surveys to predict next years populations and levels of defoliation are currently underway.

Spruce budworm area

The spruce budworm outbreak in central Anoka County, in the Metro Region, picked up again this year where it left off from last year. The feeding damage from intense budworm activity was reported in a large residential area just north of the Andover City Hall by the Andover city forester in early July. The entire area has been developed in recent years amidst abandoned Christmas tree plantations composed of pure white spruce. Consequently, white spruce dominates the conifer component throughout this residential area. Most of the trees defoliated by the budworms were between 25 and 50 feet tall.

Usually confined to the northern and central parts of the state, the Anoka County outbreak is now in its sixth year and has several homeowners in the area quite concerned and wondering what they can do to save their trees. In fact, the outbreak has helped the city forester bring several of these concerned neighbors together in an effort to work together in getting some help with this ongoing problem.

Pine spittlebug on balsam fir

The pine spittlebug, Aphrophora parallela (Say), is "often abundant on white, jack pines as well as other conifers". Other conifers being balsam fir, tamarack and spruce. And in fact, several Christmas tree growers in the north central counties reported the occurrence of this insect in their balsam fir fields this summer.

Pine spittle bug Pine spittle bug

Spittlebug eggs overwinter on the tips of twigs. On hatching in the spring, the young pierce the bark to feed on the sap and soon cover themselves with a frothy mass of spittle made up of tiny air bubbles coated with the partially digested sap . The bubbles protect the insect and are formed by a series of movements of the abdomen while the young spittlebug is feeding. From May to July, the young move periodically inward on the branch and when full grown, in July, they have usually reached the main stem where many bugs often feed together under large masses of spittle. When the young change to adults in July, the spittle masses soon dry up and a black sooty mold often develops at feeding sites. The adults, which are from to ½ inch long, also feed on the tree's sap throughout July and August but do not form spittle. They do, however, eject undigested sap in the form of a fine mist that drops from heavily infested trees like very light rain. Then sooty molds can infest the honeydew.

Heavy infestations of spittlebugs may cause twig, branch and tree mortality the following year. In natural stands, spittlebug population build-up is often prevented by a fungal disease caused by Entomophthora aphrophora. In plantations, control may be required and since the spittle masses give protection to the young, contact insecticide sprays must be applied with force before mid-July.