SUMMARY OF IIAIUTS AXD (MI A R ACTKIMSriCS. \ '.] 
of tliis |)(M'iiliarit y, assiiinini:; it to \)o ahiioi-nial, we can at l(»as( sec 
certain advantau^cs coniiiiii; to the species therelVoin. Anionir tlicsc 
are tlie j)roteetion from attacks of parasitic enemies. >incc w c can 
hardly concei\(^ of a |)arasite limited to this Cicada which could pos- 
sihly extcMid its c>\istence ovei" an e(pial t(M'm of years. lis occui'- 
renc(\ also, in overwhelming:; nnnd)ers at almost the same moment 
everywhere" within \\\c ranii;e of llic hrood picviMits its heinii; \ ci'V 
often seriously cliecked in its achdt slag-e hy th(> attacks of hirds 
and oth(»r vertebrate enemies, whieli fatten on it in enormous num- 
hcM's. For tliis si)eeies this is a most impoi'tant consi(l(M-at ion. foi- ii is 
iiatui-ally shii::,i2:i>^h and lielpk^ss and seems to hick ahnost complcicly 
the instinct of fear common to most other insects, and this lca\c> it 
an easy prey to insectivorous animals. The ahnost (Mitin^ al)scnc(> of 
fear and consecjuent effort to save itself from danger by lli^rht or 
concealment is apparently a consequence of the long intervals between 
its aerial appearances. 
The ii^reatest check on the species has been in the advent of Euro- 
peans on this ccnitinent and the accompanying clearing of woodlands 
and increase of settlement. The vast areas in the more densely popu- 
lated East, wliicli were once thickly inhabited by one or the other of 
the broods of the periodical Cicada, are rapidly losing this character- 
istic, and the Cicada w ill doubtless appear in fewer and fewer numbers 
in all settled districts. A recent important factor wliich is assisting 
in this ])articiilar is the English sparrow, and it has been shown by 
Professor liiley and later observers that in and about cities nearly all 
of the few^ cicadas which still emerge under these more or less unfavor- 
able conditions are devoured by this voracious bird. On the other 
hand, as stated (p. 58), the first brood of these insects to be noted 
by the early New England colonists, namely, the swarm recorded for 
Plymouth for 1634, was just as abundant in 1906, the year when it 
last recurred, as ever. This is, however, not the normal condition. 
the wooded areas having been considerably maintained in Plymouth 
and Barnstable counties, wdiereas ordinarily such wooded areas have 
been greatly reduced or obliterated, and the Cicada in consecpKMicc 
slowly exterminated. 
The rapid disappearance of the Cicada, as a result of the clearinir of 
forest areas and the conditicMis which accompany settlement, is nota- 
bly shown in the case of Brood XI, wdiicli formerly occupied a comj)a(t 
territory in the valley of the Connecticut River in the States of Massa- 
chusetts and Connecticut. In a letter to th(* writei-. Mr. rieori^c 
Dimmock, who has made a special study oi this brood in i he northern 
part of the town of vSuf field, Conn., says: "When I saw them in 1S(H) 
the cicadas were so abundant tliat small 1)iishes and undei-growth in 
the rather sparse woods in wliich they occurred were weighted down 
with them." In 1886 he was unable to visit the region, but was 
