834 CHARLES PauL ALEXANDER 
SEASONAL DISTRIBUTION 
Like many other groups of insects, the Holarctic crane-flies have 
a remarkably constant seasonal distribution, there being vernal, early 
summer, midsummer, and autumnal species, as well as forms that range 
over a much longer period. The vernal species appear soon after the 
melting of the ice in spring, and are on the wing for a month or two. 
Some few of these species reappear in late summer, and these are pre- 
sumably double-brooded species. In New York, New England, and 
southern Canada the great majority of crane-flies are on the wing during 
the month of June. Among these are represented the last of the vernal 
forms and the first of the extensive midsummer fauna. In late summer 
a few additional species appear, and these are closely followed in Sep- 
tember and October by about the same number of autumnal forms. The 
winter crane-flies, so-called, include species of Trichocera and Chionea 
which appear at other seasons of the year as well but are more easily 
detected during the mild, sunny days of winter. 
In general it may be stated that the crane-flies of eastern America 
which fly in spring and summer come out later and disappear earlier in 
the northern part of their range — New York, New England, and southern 
Canada — than in the southern part — the Middle Atlantic and Southern 
States. The late summer and the autumnal species, however, come 
out earlier in the former regions than they do farther south, and disappear 
correspondingly early in the season, their period being restricted by the 
date of the first killing frost. 
The dates as here given apply to the Transition areas of New York 
and New England. They should be considered as earlier in the vicinity 
of Washington — from one to three weeks or even more, depending on 
the situation —and later as one goes northward, with the exceptions 
given above. It must be understood and expected that considerable 
deviation from these dates and figures will be found, but it is believed 
that in most cases they are fairly accurate; bemg based on a vast number 
of records extending over many years. 
The following are early to late spring species —from April 1 thru 
May, disappearing about the first of June but many of them reappearing 
in August and September. Most of these species appear for the first 
time about April 20. Helobia appears much earlier, in March or even 
in February. The species of Ormosia, Dicranota, and Rhaphidolabis are 
