258 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
wings haa the basal half rosy red, fche entire costa and outer half gray, with the 
markings of tin- upper Bids faintly reproduced. The under Hide of the hind wings is 
gray and crossed by alternate bands of brown and whitish. The males have the 
antenna- strongly biper filiate. (Fernald.) 
33. TllK SAG-WORM* 
Thyridopttryx ephemeraformis (Haw.). 
The following account is taken from Professor Riley's bulletin on 
shade-tree pests (So. 10, Div. of Eut., U. S. Dept., Agr.) : 
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. 
The eggs.— During winter-time the dependent sacs 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 pupa), which is 
tilled with numerous small, yellow eggs (Fig. 96 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 condition the eggs remain from fall throughout the winter and 
early spring. 
*sf> 
n Mm 
F\r,. 96.—Th>/ridopteryx ephemerceformis . a, larva: b, male chrysalis; c, female moth ; rf, male moth; 
t, follicle ami pupa cut opeu to show ep<;s; /. full grown larva with bag; <j. youug larva- with 
their conical upright coverings; all natural size. After Riley. 
The larva and its to?.— About the middle of May in this latitude the eggs hatch 
into small but active larva\ which at once commence to construct a portable 
or bag in which to live. The way in which this bag is prepared is curious (Fig. 97). 
The young larva crawls on a leaf and, gnawing little bits from the surface, fastens 
these together with fine silk spun from its mouth. Continually adding to the mass, 
the larva finally produces a narrow, elongate band, which is then fastened at both 
ends onto the surface of the leaf by silky threads. Having secured itself from fall- 
ing down by some threads, it now straddles this band and, bending its head down- 
