50 
EASTERN SHADE TREE CONFERENCE 
THE SPRUCE SAWFLY (.Diprion polytomum HTG.) AND 
THE EUROPEAN PINE SHOOT MOTH 
(Rhyacionia buoliana SCHIFF.) 
By R. B. Friend, Agricultural Experiment Station , New Haven , Conn , 
This meeting is devoted to the discussion of shade tree problems, and 
my remarks about these two pests of conifers, the spruce sawfly and the 
pine shoot moth, will be confined largely to their importance to shade 
trees rather than to forests. Both species are European in origin, and 
both can seriously affect the appearance and vitality of their hosts. 
The pine shoot moth infests most native and exotic pines to a greater 
or less extent. Red, mugho and Scotch pines are the favorite hosts 
among our common species. Austrian and Corsican pines are sometimes 
well infested, although rarely to such an extent as the two species just 
mentioned. White pine has never been found badly injured, and the 
effect of the insect on this tree is of no significance. Ponderosa pine, a 
rather rare tree in this region, has been found a good host plant in the 
few cases which have come under observation. 
The adults of the pine shoot moth fly in June and the first half of 
July, the peak of flight occurring the last week in June. The eggs are 
laid on the twigs near the tips and hatch in about 10 days. During the 
early summer the larvae bore into the bases of the needles at the tips of 
the twigs, and the presence of dead tip needles at this time is an indica¬ 
tion of infestation. After a period of about three weeks in the bases of 
the needles, the larvae crawl to the tip of the twig and bore into the buds. 
Their presence is indicated by masses of pitch which exude from the 
tunnels. In the buds or under pitch masses on the buds they spend the 
winter. In the spring the bored buds are vacated and growing shoots 
are attacked. An infested shoot bears a mass of pitch on one side, 
becomes characteristically curved, and in the majority of cases, but by 
no means always, dies. If the shoot survives, it is distorted, and as 
far as observations in this country show, the crook is permanent. The 
pupal stage occurs in the shoots in May and June. 
The injury caused by the shoot moth to pine trees is influenced by 
several factors. The tops of pines are more heavily infested than the 
lower branches, and isolated trees are more heavily infested than trees 
planted so close together that their branches touch when a height of 10 
feet is reached. Even closely planted trees are subject to heavy infesta¬ 
tion when small, being then isolated for all practical purposes. If a 
