12 NORTH AMERICAN ACRIDIIDiE. 



by a wingless species, Podisma glacialis variegata, whose presence 

 is believed to indicate the southward extent of continuous sub- 

 alpine conditions in the Glacial Epoch. 



NUMBER OF BROODS. 



Notwithstanding the great length of the season of active life in 

 the Lower Austral zone, there is, so far as I have been able to learn, 

 but one brood per annum of any species of locust inhabiting the 

 Eastern States; at least, I have failed to secure definite proof of 

 the occurrence of two broods in any case, though it seems not im- 

 probable that Chortophaga viridifasciata and possibly other species 

 may have two broods in the extreme south. This is a point which 

 might readily be determined by resident observers in Florida or 

 along the Gulf coast. 



Contrary to the opinion sometimes expressed, the presence of 

 very young or of adult insects in widely separated months of the 

 year does not prove that there are two broods per annum of that 

 species, unless, possibly, in the extreme south, where there is no 

 inactive winter resting season. It needs to be shown that adults 

 appear in numbers twice per annum, alternating with two similar 

 appearances of newly hatched young, in order to establish beyond a 

 doubt the occurrence of two broods annually in the life history of 

 a species. 



LIFE HISTORIES. 



There is much variation in individuals of the same species in 

 the time of hatching ; and in different species in their life history 

 with reference to the seasons of the year, some passing the winter as 

 adults, some as nymphs, but by far the most in the egg stage. 

 Schistocercaamericana ^Leptysma marginicollis, and several Tettiginae 

 are examples of the first ; in the Northern States Chortophaga 

 viridifasciata, Arphia sulphurea, and Hippiscus iuberculatus are 

 examples of the second. It seems not impossible that some long- 

 lived species may occur as adults in every month of the year in 

 some of the warmer zones. In reference to this point observations 

 are needed during the entire year. 



ZONAL DISTRIBUTION. 



Owing to the lack, in many cases, of definite data, the follow- 

 ing statements concerning the zonal origin and distribution of the 

 genera of Acridiidae of eastern North America must be regarded as 

 purely tentative, to be corrected and revised as opportunity permits. 



