6 BULLETIN 1238, XT. S. DEPARTMENT OF AGRICULTURE 



In addition to the host plants already noted, the spring canker- 

 worm has been recorded as feeding on the following hosts : 



Betula alba L European white birch. 



Hicoria glabra (Mill.) Britton Pignut. 



Hicoria ovata (Mill.) Britton Shagbark hickory. 



Catalpa speciosa Warder Western catalpa. 



Fraxioius americana L White ash. 



Fraxwius nigra Marsh Black ash. 



Gleditsia triacanthos L Honey locust. 



Ligustrum vulgare L Privet. 



Prunus cerasus L Sour cherry. 



Prunus pensi/lvanica L. f Pin cherry. 



Prunus domestica L Plum. 



Pyrus ioensis (Wood) Britton Prairie crab. 



Quercus macrocarpa Michx Mossycup oak. 



Quercus muhlenbergii Engelm Chinquapin oak. 



Quercus palustris DuRoi Pin oak. 



Quercus borealis maxima (Marsh.) Ashe Red oak. 



Rosa setigera Michx Prairie rose. 



Rosa spp Roses, cultivated varieties. 



In addition to the host plants listed as common to both species, 

 the following have been recorded for the fall cankerworm : 



Juglans cinerea L Butternut. 



Prunus avium L Mazzard. 



Prunus serotina Ehrh Black cherry. 



DISTRIBUTION. 



It has been difficult to determine from the literature the exact 

 limits of the distribution of the respective cankerworms, since many 

 accounts are indefinite as to the identity of the species under con- 

 sideration. The approximate distribution of the two species is shown 

 in the maps (figs. 1, 2) and is as follows: 



FALL CANKERWORM. 



The fall cankerworm occurs in the northeastern United States 

 from North Carolina, Kentucky, and Missouri northward into south- 

 ern Canada as far west as Manitoba, and along the northern border 

 of the United States through the States of Minnesota, North Dakota, 

 and Montana. It has also been reported from Colorado and Cali- 

 fornia. 



SPRING CANKERWORM. 



The spring species is found throughout the northeastern and north- 

 central part of the United States. It has been reported in the ex- 

 treme southern part of Canada from Nova Scotia to Lake Huron, 

 and also in Manitoba. The western limit of the main area of infesta- 

 tion seems to be Manitoba, Minnesota, Nebraska, Colorado, and Okla- 

 homa. It has been recorded as far south as Jacksonville, Tex.; 

 Arkansas, Tennessee, and North Carolina. It has also been found 

 in California. 



MEANS OF DISSEMINATION. 



Owing to the wingless condition of the female moths, the natural 

 spread of the cankerworms is very slow. This accounts for the oc- 

 currence of isolated infestations and their slowness in extending over 

 additional territory. The cankerworms are carried to new localities 

 largely by three methods. (1) The tiny recently hatched larvae 

 often spin down on threads and are blown about by the wind. The 



