r 
- ; THE BA i-WORM. 23 
THE BAG-WORM. 
(Thyridopteryx ephemereformis Haw.) 
Although this species was not particularly destructive to our shade- 
trees in 1886, and in numbers greatly inferior to the Fall Web-worm 
and the Tussock-moth, yet in 1879 it was much more formidable, and 
at irregular intervals becomes a great pest where not properly dealt 
with, especially in more southern States. For the past two or three 
years it has been on the increase in special localities in Washington, 
and should be carefully looked after. 
HABITS AND NATURAL HISTORY. 
The Hggs.—During winter time the dependent saes or bags of this 
species may be seen hanging on the twigs of almost every kind of tree. 
If they happen to be on coniferous trees, and they are usually more 
abundant on these than on deciduous trees, they are not infrequently 
mistaken for the cones. In reality they are the coverings spun by our 
worm, and they serve not only as a protection to it, but also to the 
eggs. Upon cutting open the larger of these bags in winter time they 
will be found to contain the shell of a chrysalis (technically called the 
puparium), which is filled with numerous small yellow eggs (Fig. 7 e). 
Each of these is a little over 1 millimeter in length, obovate in form, 
and surrounded by a delicate, fawn-colored, silky down. In this con- 
dition the eggs remain from fall throughout the winter and early spring. 
Fic. 7.—Thyvidopteryx ephemereeformis: a, larva; b, male chrysalis; c, female moth; d, male moth; 
é, follicle and puparium cut open to“show eggs; f, full grown larva with bag; g, young larve with 
their conical upright coverings; all natural size. 
The Larva and its Bag.—About the middle of May in this latitude the 
eggs hatch into small but active larve, which at once commence to con- 
