274 



^.V ECONOiMIC ENTOMOLOGY. 



In the spring these eggs hatch, and the Uttle larvie make their 

 way out through the mouth of the bag and feed upon the leaves, 

 at once constructing for themselves a case made of leaf fragments 

 held together with silken threads. At this time the bags are 

 carried upright, and the insects feed on the upper surface of the 

 leaf. As the larva grows it enlarges its habitation, which soon 

 becomes too heavy to be maintained in an upright position, and 



IMG. 298. 



The bag-worm, Thyridopteryx ephrmerirformis.—a, larva: b, male pupa: c, female, 

 d, male moth ; e, bag of female cut open to show the mass of eggs ; f, caterpillar with 

 bag in normal position ; g, young larvae with bags carried upright. 



drops ; the insect continues to feed, attaching the bag by means 

 of silken threads to twigs when not moving about from place to 

 place. Late in summer the larvae become full grown, and 

 wander, sometimes leaving the trees altogether and fastening to 

 fences or other shelter in the vicinity, and it is this habit that 

 provides for the spread of the insects. When they have reached 

 a place that suits them, the bags are firmly fastened, the opening 

 is closed, and the caterpillars change to pupre. Shortly after the 

 male emerges, and this is a black moth with transparent wings, 

 short, feathered antennae, and an unusually long, tapering bod\-. 

 It is quite active and seeks the female, which forms only an 

 imperfect sort of pupa, and even in the adult condition is a non- 

 descript without trace of wings and almost without antennae. 



