growing regions of the eastern States from Maine to North Caro- 
lina and Minnesota. Paper birch appears to be the favored host, 
but several other birches and possibly alder are also attacked. The 
adult has a brown and white body and a wingspread of about 9 
mm. The forewings are marked with diagonal white bars and the 
hindwings have broad fringes of hair. Full-grown larvae are yel- 
lowish-green, with hairs projecting from white tubercles, and 
are about 6 mm. long. 
Adults are active from late June to late July and lay their 
eggs singly here and there over the leaves. Hatching occurs in 
about two weeks and the young larvae enter the leaves to feed, 
forming serpentine mines. Three or four weeks later they emerge 
through the lower surface and spin webs within which they molt. 
After molting, they leave the webs and feed externally as skele- 
tonizers until they reach maturity. Full-grown larvae drop to the 
ground and spin short, brown cocoons in which they spend the 
winter on the undersides of fallen leaves or other debris. There 
is one generation per year. 
Outbreaks occur at frequent intevals, often over large areas, 
and last for 2 or 8 years. Defoliation may be severe but it seldom 
causes much tree mortality. The defoliated trees may be so seri- 
ously weakened, however, that they are attacked and killed by the 
bronze birch borer. 
The oak skeletonizer, Bucculatrix ainslhiella Murt., occurs from 
southern Canada and the Lake States to North Carolina and 
Mississippi. Its hosts are various species of oak and chestnut. 
The adult has a wingspread of 7 to 8 mm. The forewing is largely 
blackish, with paler areas outlining an oval, blacker patch on 
the inner margin. Full-grown larvae are yellowish-green and 
about 5 mm. long. 
The winter is spent in the pupal stage in cocoons. The cocoons 
are white, about 3 mm. long and ridged longitudinally. Adults are 
active in April and May and again in July and August. Eggs are 
laid on the undersides of leaves. First-instar larvae enter the 
leaves to feed, forming serpentine or blotch mines. Older larvae 
feed externally on the lower surface, often completely skeletoniz- 
ing the leaves (fig. 164) (287). Two generations per year have 
been recorded in Michigan and Massachusetts. Outbreaks occa- 
sionally occur over large areas. 
Other widely distributed species of Bucculatrix and their hosts 
are as follows: B. packardella Chamb.—various oaks and occa- 
sionally beech; B. quinquenotella Chamb.—oaks; B. luteella 
Chamb.—white oak; B. recognita Braun—various white oaks, 
preferably bur, and B. coronatella Clem.—black birch. 
FAMILY PSYCHIDAE 
BAGWORM MoTHS 
Members of this family have the interesting habit of spending 
the entire larval stage within silken bags. The bag is usually 
strong, tough, and camouflaged by an outer layer containing bits 
of twigs and leaves. Newly-hatched larvae begin to spin bags 
about their bodies as soon as they start to feed and they continue 
410 
