EEPORT OF THE ENTOMOLOGIST. 519 



at iiiglit, 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 eggs being laid by 

 the end of May. 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 become more and more conspicu- 

 ous. The second brood of moths begins to appear in July, and its 

 occurrence 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 September, hatching most extensively, 

 however, about the first of August. 



In Massachusetts and other JSTorthern 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 Sep- 

 tember. 



The following general remarks upon the different stages refer to 

 Washington and localities where the same conditions hold. 



The Eggs (Plate X, Fig. 3a). — 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 con- 

 sists 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 394, 

 427, and 503, or an average of 441 eggs. But in addition to such 

 large clusters each female will deposit eggs in smaller and less regu- 

 lar patches, so that at least 500 eggs may be considered as the real 

 number produced by a single individual. The egg, measuring 0.4"'", 

 is of a bright golden-yellow color, quite globular, and ornamented by 

 numerous regular pits, which give it under a magnifying lens the 

 appearance of a beautiful golden thimble. As the eggs approach 

 the time of hatching this coloii 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 considerably, and the latter may be 

 greatly retarded by inclement weather. Usually, 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 moth might in a single 

 season (assuming one-half of her progeny to be female and barring 

 all checks) number 125,000 caterpillars in early Fall — enough to ruin 

 the shade trees of many a fine street. 



The Larv^ (Plate X, Figs. 2a, 2b, and 2c).— The caterpillars just 

 born are pale yellow, with two rows of black marks along the body, a 

 black head, and with quite sparse hairs. When full grown they gen- 

 erally 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, very 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. 



