518 REPORT OP THE COMMISSIONER OF AGRICULTURE. 



THE FALL WEB-WORM. 

 (HyphanU'ia cunea, Drury.)* 



Order Lepidoptera; family Bombycid^. 

 [Plates X and XI.] 



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

 great injuries 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 numer- 

 ous. 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 report we first called 

 attention 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 attention. 



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 188G, 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 general 

 that the first brood appears soon after the leaves have fully devel- 

 oped, 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 wan- 

 der about seeking places for transformation from the end of August 

 to the end of September. 



The species invariably hibernates in the chrysalis state within its 

 cocoon, and the issuing of the first brood of moths is, as a conse- 

 quence,_ tolerably regular as to time, i. e. , they will be found issuing 

 and flying slowly about during the evening, and more particularly 



* We have adopted the name Hyphantria cunea, following Clemens's reasons for 

 separating Hyphantria from Spilosoma. He shows (Proo. Ac. Nat. Sci. Phil., 1860, 

 p. 580) that, while agreeing in tlie wings, Hyphantria ditfers in the labial palpi, the 

 second .joint of which is very short and the terminal joint nearly rudimentary, and 

 in the hind tibioi, which have but one pair of small apical spurs. 



The following is the synonymy of the species: 



Phalcena {Bomhyx) cunea Drury, 1782. 



Phalcena punctatissima Abbott and Smith, 1797. 



Cycnia cunea Huebner, 1821. 



Spilosonta cunea (Drury), Westwood's Ed. Drury, 1837. 



Hyphantria textor Harris, 1841. 



Eupr'octis textor {Havrifi); Walker, 1855. 



Hyphantria punctata Fitch, 1856. 



Hyphantria textor Harris, Clemens, 1861. 



Spilosoma cunea Drury, Brooklyn Soc. Check-list of Macro-Lep., 1882. 



Hyphantria cunea (Drmy), Grote's Check-list, 1882. 



