HOWE: NEW ENGLAND ODONATA 113 
the other hand, have as a rule a long flight season extending from 
June to September, or through two seasons. The three periods 
are not co-extensive throughout New England, for in interior 
Maine and in high elevations spring extends from early June to 
early July; summer from early July until mid-August; and autumn 
from mid-August until mid-September. Along the southern coast 
of New England, on the other hand, spring extends from late April 
until mid-June; summer from mid-June until late August, and 
autumn from late August even to mid-November ^ (Banks, Ann. 
Ent. Soc. Amer., 8 : 133-134, 1915). 
Studies in botanical ecology have progressed farther than those 
in zoological ecology, and no ecological study of the Odonata as a 
whole has been seriously attempted (see Calvert, Proc. Acad. Nat. 
Sci. Phila., 60: 460-491, 1908). Dr. Needham in his Aquatic In- 
sects of New York (Bull. 68, N. Y. State Mus., 275, 1903) listed 
the larval habitats "of some New York Odonata," and Dr. Riley 
has published a paper (Ann. Ent. Soc. Amer., 5 : 273-292, 1912) 
on the Ecology of Odonate Nymphs, and various other writers, in- 
cluding the author, have stated the imaginal habitats of the species 
listed. That in a study of the distribution of species a great deal 
of investigation might well be spent on ecological areas is perfectly 
evident. An explanation of the distribution of certain puzzling 
species may be solved by an understanding and recognition of the 
so-called "lakes." Williamsonia lintneri for example, known from 
the semi-boreal prairie Provinces of Ontario and Manitoba, again 
occurs not uncommonly in eastern Massachusetts in what has been 
considered as the Transition Zone, with additional records from 
Center, N. Y., and Paterson, N. J., stations on the boundary of 
the so-called Upper Austral. It is without doubt a boreal species, 
and flies in eastern Massachusetts in April and May. Here it has 
been taken about cold boggy ponds and quarry pools. Thus are 
represented two widely separated distributional "lakes." 
In the distribution of Odonata in New England there is only 
one striking and seemingly very definite line that separates two 
New England regions for both Boreal and Austral species. This 
is the glacial contact line or interlol)ate moraine stretching from 
Manomet to Falmouth, — a l)arrier in other words to Cape Cod. 
' These terms are applical)le only to New EnglamI, — si)riiig species are 
frequently summer species in Canada. 
