258 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



wings has the basal half rosy red, the entire costa and outer half gray, with the 

 markings of the upper side faintly reproduced. The under side of the hind wings is 

 gray and crossed by alternate bands of brown and whitish. The males have the 

 antennae strongly bipectinate. (Fernald.) 



33. The bag-worm. 



Thyridopteryx ephemerocformis (Haw.). 



The following account is taken from Professor Riley's bulletin on 

 shade-tree pests (No. 10, Div. of Ent., 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 j'ears 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 

 filled with numerous small, yellow eggs (Fig. 9G 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. 



Fir.. 96. — Thjiridopteryx ephemerceformis : a, larva: h. male chrysali.s; c, female moth ; rf, male moth; 

 e, follicle and pupa cut open to show eggs; ./", full grown larva with bag; g, young larvae with 

 their conical upright coverings; all natural size. After Riley. 



The larva and its bag. — About the middle of May in this latitude the eggs hatch 

 into small but active larvse, which at once commence to construct a portable case 

 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- 



