SPRUCE BUD-WORMS. 847 
29. The black-headed spruce bud-worm.* 
Teras variana Fernald. 
This caterpillar is so commonly met with on the spruce and fir that we 
have given it the above English name, though there are other species 
which have green bodies and black heads. We first met with it on the 
terminal shoots of the black spruce on Peaks Island, in Portland Har- 
bor, June 22, 1881, and also at Brunswick and Harpswellon the day 
following, where it was associated with the caterpillars of the Spruce 
Bud- worm (Tortrix fumiferana). Unlike that species it does not, so far 
as we have observed, cause any decided alteration in the appearance 
of the shoots of the tree, not being social or abundant enough to strip 
the leaves from a single shoot, as in the case of the Spruce Bud- worm, 
or the Reddish-yellow Spruce Bud-worm (Steganoptycha ratzeburgiana) 
found on the white spruce last season. 
The egg-laying habits are not yet known, as none of the moths on 
issuing from the chrysalis mated or proceeded to deposit eggs. 
The caterpillars usually live near the ends of the shoots, feeding on 
the new leaves, which begin to grow out early in June ; cutting off the 
tender leaves they make a passage way between them and the shoot, 
which they line with white silk. When disturbed they rapidly crawl 
out of their silken retreat and let themselves down to the ground by a 
silken thread. They are very active in their habits and in confinement 
in tin boxes will squeeze through the narrow space between the box and 
the cover, so that only an unusually tightly closed box will confine 
them. Sometimes, at least in two instances, the caterpillars constructed 
a case of the leaves which they had cut off at the end of a fresh bud. 
The caterpillars were very abundant in 1881 in spruce and firs on 
the shores and islands of Casco Bay, from June 10 until July 20. As 
full-grown larv?e are abundant during the early part of June, it seems 
that it hibernates among the shoots of the tree during the winter, and 
that as in the case of the Spruce Bud-worm (Tortrix fumiferana) it 
hatches in August, or at least late in the summer, and becomes nearly 
fully grown before cold weather sets in. 
The caterpillar when fully grown is of the usual shape of a leaf-roller, 
deep green, with a dark reddish head and cervical shield ; before the 
last molt the head and prothoracic or cervical shield are black. 
From the 14th to the 16th of June the caterpillars change to chrys- 
alids within the slight white cocoon they spin among the bases of the 
leaves next to the shoot. The moths begin to issue early in August, 
and continue to appear until the middle of the month. In one case the 
insect pupated from July 6th to the 10th, the moth issuing on the" 19th ; 
hence the pupal period lasts about two weeks. Others which pupated 
July 14 to 16 appeared three weeks later. None of the insects lingered 
•Extracted from U. S. Department of Agriculture, Division of Entomology, Bulle- 
tin No. 12, p. 17. 
