48 



BULLETIN 1103, U. S. DEPARTMENT OF AGRICULTURE. 



sect at present. This maj- have a considerable influence in lessening- 

 the ravages of this species. 



Two of the introduced enemies of the gipsy moth are vigorously 

 attacking this host, namel}^, GMnpsilura concinnata Meig. and 

 Calosoma sycophanta L. These two enemies are undoubtedly re- 

 sponsible for the checking of the damage done by the satin moth. 

 Three native tachinid flies are also commonly bred from the larvae of 

 the species — Tachina mella Walk., Euphorocera claripennis Macq.,. 

 and Winthemia quadnpustulata Fab. Telenomus calif ornimi^ Ashm. 

 has been reared from the eggs. 



The solid area on the map (Fig. 26) indicates the region infested 

 in 1920, while the uncolored named towns are the additional ones- 

 infested during 1921. 



Table 11 gives the departures from normal temperature and rain- 

 fall in New England in 1920-21. 



Table 11. — Monthly departures of temperature and rain-fall in New England for 

 the fall of 1920, the icinter of 1920-21, and the groicing season of 1921, used' 

 in connection with the 1921 summary of the gipsy moth, the brown-tail moth,^ 

 and the satin moth. 



DEPARTURE 



(IN DEGREES FAHRENHEIT) 



FROM 



NORMAL 



TEMPERATURE. 





1920 



1921 





Sept. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



May. 



June. 



July. 



Aug. 



Sept. 



New England 



+ 1.7 



+6.2 



-1.4 



+2.9 



+ 3.4 



+3.5 



+9.4 



+ 5.6 



+0.8 



+0.0 



+3.0 



-1.5 



+3.3 



DEPARTURE (IN INCHES) FROM NORMAL RAINFALL. 



New England . 



+2.00-1.68i + 1.09' + 2. 19 



-1.48-0.55 



-0.64 



+0.77 



-0. 76 -0.53 +1. 10|-L 02,-1. 12 



GIPSY MOTH. 



{Porthetria dispar L.)' 



The gipsy moth, during 1921 and for a series of years preceding, 

 has met with adverse conditions along its northern and northeastern- 

 borders of distribution. The weather conditions in the spring are 

 usually favorable, when small larvae are being carried by the wind,, 

 for its rapid dispersion in these directions, but the line of advance- 

 ment is considerablj^ impeded by the rapid change in the type of 

 forest growth, the proportion of hardwoods to conifers changing" 

 rapidly. Large areas of practically clear coniferous growth are un- 

 favorable to the development of larvae, and such growth is found 

 more or less in the regions mentioned above. Another serious: 

 obstacle in the more northern regions is the prevailing low tempera- 



^ By A. F. Burgess, Bureau of Entomology. 



