NATIKAL KNKMIKS. 127 
their tMiuM-LTiMice the ti-(H's thoinselvos (\\hil)it(Ml a iriunl stato of viLTor 
aiul an inspcHiion of the roots rovoahMl n(» in:it(>ri}il iiijurx mixc some 
small swelliiiLrs or eallosities with sliuht (hscoloi-nt ion which miirht 
have resulted IVoin the piiiu'tiii'es. 
The uiuleruroinul (h^N'elopment of the Cicada is so \c\\ slow . 1 liiiiccii 
or seventeen years heinu: oecupiiMl in nttniniii^n size which wiili oilier 
speeies is aeliievcul in as many days or ^\('eks, that the xciy slow 
ahsorption o\' nutriment from th(> roots can scarcely have an\- clh'ct 
on them, and the only injury, and this-is very slight, is prohahly due 
to a poisoning of the roots, perha])s hy the beak of tjie insect, as 
indicated by the slight discoloration of the cambium at the point of 
puncture. Callosities and other irregularities are, however, rare, 
and have never been observed by the writer. Very often also there 
are, undoubtedly, long periods of rest or dormancy, during which no 
food at all is taken. 
Referring to the injury noted by Miss Morris, it is a well-known 
fact that fruit trees have a natural term of life, and after twenty years 
they are very apt to show weakness and loss of vigor, and cease to be 
profitable. It is .possible, therefore, that this is the true explanation 
of the condition of the trees noted by her rather than that it was due 
to the presence of the larva? of the Cicada. 
THE NATURAL ENEMIES OF THE CICADA. 
The fact that the periodical Cicada appears above ground so rarely 
prevents its having any peculiar or specific parasitic or natural 
enemies. We can not conceive of any parasite breeding solely. either 
in the adult Cicada or in its eggs which could persist during the long 
period of years when no host w^as available. Equally remarkable 
also would be a parasitic insect the term of whose life should be so 
extended that it could live in the body of the Cicada larva during 
the years of its slow- growth beneath the soil. Of the larger enemies 
of the Cicada, such as bii'ds and mammals, the habit of feeding on 
the Cicada is necessarily acquired anew with each recurrence of a 
Cicada year. 
All these facts have a very potent influence^ in protecting the ])eri- 
odical Cicada, which, as we have already pointed out, is j^articularly 
helpless, and were it not for these natural protective influences the 
very existence of the species would probably be early brought to 
an end. 
During their subterranean existence, the larvie and pu})a?, when 
near the surface, are doubtless subject to the attacks of various 
predaceous coleopterous larvae, and many of them are unquestionably 
destroyed l)y this agency. Upon leaving the ground to transform 
they present an attractive food for many insectivorous animals, and 
the pu])a^ and transfoi'ming adults are vigorously attacked by many 
