36 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 



THE FALL WEB-WORM. 



(Hyphantria cunea, Drury.) 



"This insect has from time to time attracted general attention by its- 

 great injury to both fruit and shade trees. Many authors have written 

 about it, and consequently it has received quite a number of different 

 names. The popular name ' Fall Web-worm,' first given to it by Harris, 

 in his 'Insects injurious to Vegetation,' is sufficiently appropriate as 

 indicating the season when the webs are most numerous. The term is, 

 however, most expressive for the New England and other Northern 

 States, where the insect is single-brooded, appearing there during 

 August and September, while in more southern regions it is double- 

 brooded. In our Third Missouri Eeport we have first called atten- 

 tion to its double-broodedness at Saint Louis, and we find that it 

 is invariably two brooded at Baltimore and Washington. Except 

 in seasons of extreme increase, however, the first brood does no wide- 

 spread damage, while the fall brood nearly always attracts atten- 

 tion. 



"We have decided to call attention to this insect somewhat in detail 

 in this report, because of its exceptional prevalence and injury in the 

 Atlantic States during the year 1886, and because it became a public 

 nuisance in the city of Washington, and the District Commissioners 

 have formally requested information from us on the subject." 



NATURAL HISTORY. 



Limitation of Broods. — "At Washington we may say in geueral that 

 the first 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 Sep- 

 tember. In Massachusects 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 seek- 

 ing places for transformation from the end of August to the end of Sep- 

 tember. 



"The species invariably hibernates in the chrysalis state within its 

 cocoon, and the issuing 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, dur- 

 ing 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 





