53 



Limitation of Broods.— At Washington I may saj' in general that thetirst brood appears 

 soon after the leaves have fully developed, and numerous webs can be found about the 

 first of June, while the second brood appears from the middle of July on through August 

 and September. In Massachusetts and other Northern States the first moths issue in June 

 and July; the caterpillars hatch from the last of June until the middle of August, reach 

 full growth and wander about seeking places for transformation from the end of August 

 to the end of September. 



The species invariably hibernate in the chrysalis state within its cocoon, and the issu- 

 ing of the first brood of moths is, as a consequence, tolerably regular as to time, i. e., they 

 will be found issuing and flying slowly about during the evening, and more particularly 

 at night, during the whole month of May, the bulk of them early or late in the month, 

 according as the season may be early or late. They couple and oviposit very soon after 

 issuing, and in ordinary seasons we may safely count on the bulk of the egg being laid by 

 the end of Maj^ During the month of June the moths become scarcer, and the bulk of 

 them have perished by the middle of that month, while the webs of the caterpillars be- 

 come more and more conspicuous. The second brood of moths begins to appear in July, 

 and itsocurrence extends over a longer period than is .the case with the first or spring 

 brood. The second brood of caterpillars may be found from the end of July to the end of 

 Seiitember, hatching most extensively, however, about the first of August. 



The following general remarks upon the different stages refer to Washington and local- 

 ities where the same conditions hold: 



The female moth deposits her eggs in a cluster on a leaf, sometimes upon the upper and 

 sometimes on the lower side, usually near the end of a branch. Each cluster consists of 

 a great many eggs, which are deposited close together and sparsely interspersed with hair- 

 like scales. In three instances those deposited by a single female were counted. The 

 result was three liundred and ninety-four, four hundred and twenty-seven, and five hun- 

 dred and two, or an average of four hundred and forty-one eggs. But in addition to such 

 large clusters each female will deposit eggs in smaller and less regular patches, so that at 

 least five hundred eggs may be considered as the real number produced by a single indi- 

 vidual. The egg, measuring 0.4 mm, is of a bright, golden-yellow color, quite globular, 

 and ornamented by numerous regular pits, which give it under a magnifying lens the ap- 

 pearance of a beautiful golden thimble. As the eggs approach the time of hatching this 

 color disappears and gives place to a dull, leaden hue. 



The interval between the time of depositing and hatching of the eggs for the first brood 

 varies considerablj% and the latter may be greatly retarded by inclement weather. Usu- 

 ally, however, not more than ten days are consumed in maturing the embryo within. The 

 eggs of the summer brood seldom require more than one week to hatch. 



Without check, the offspring of one female nioth might in a single season (assuming 

 one half of her progeny to be female, and barring all checks) number one hundred and 

 twenty-five thousand caterpillars in early fall — enough to ruin the shade trees of many a 

 fine street. 



The Larvx. — The caterpillars just born are pale j^ellow, with two rows of black marks 

 along the body, a black head, and with quite sparse hairs. When full grown, they gener- 

 ally appear pale yellowish or greenish, with a broad dusky stripe along the back and a 

 yellow stripe along the sides ; they are covered with whitish hairs, which spring from 

 black and orange-yellow warts. The caterpillar is, however, verj' variable both as to depth 

 of coloring and as to markings. Close observations have failed to show that different food 

 produces changes in the coloration ; in fact nearly all the various color varieties may 

 be found upon the same tree. The fall generation is, however, on the whole, darker, with 

 browner hairs, than the spring generation. 



As soon as the young caterjjillars hatch they immediately go to work to spin a small 

 silken web for themselves, which by their united efforts soon grows large enough to be 

 noticed upon the trees. Under this protecting shelter they feed in company, at first de- 

 vouring only the green upper portions of the leaf, and leaving the veins and lower skin 

 unmolested. As they increase in size they enlarge their web by connecting it with the 

 adjoining leaves and twigs; thus as they gradually work downwards their well becomes 

 quite bulky, and, as it is filled with brown and skeletonized leaves and other discolored 

 matter as well as with their old skins, it becomes quite an unpleasant feature in our pub- 

 lic thoroughfares and parks. The caterpillars always feed underneath these webs; but as 

 soon as they approach maturity, which requires about one month, they commence to scat- 

 ter about, searching for suitable places in which to spin their cocoons. If very numerous 

 upon the same tree the food supply gives out, and they are forced by hunger to leave their 

 sheltering homes before the usual time. 



When the young caterpillars are forced to leave their web they do not droji siuldenly to 

 the ground, but suspend themselves by a fine silken thread, by means of which they easily 

 recover the tree. Grown caterpillars,' which measure 1.11 inches in length, do not spin 

 such a thread. Both young and old ones drop themselves to the ground without spinning 

 when disturbed or sorely pressed by hunger. 



Pupa and Cocoo?i.— Favorite recesses selected for pupation are the crevices in liark ami 

 similar shelters above ground, in some cases even the emjity cocoons of other moths. 

 The angles of tree boxes, the rubbish collected around the base of trees, and other like 

 shelters are employed for this purpose, while the second brood prefer to bury themselves 

 just under the surface of the ground, provided that the earth be soft enough for that jmr- 

 pose. The cocoon itself is thin and almost transparent, and is composed of a slight web 

 of silk intermixed with a few hairs, or mixed with sand if nuide in the soil. 



