NATURAL ENEMIES. 127 
their emergence the trees themselves exhibited a good state of vigor 
and an inspection of the roots revealed no material injury save some 
small swellings or callosities with slight discoloration which might 
have resulted from the punctures. 
The underground development of the Cicada is so very slow, thirteen 
or seventeen years being occupied in attaining a size which with other 
species is achieved in as many days or weeks, that the very slow 
absorption of nutriment from the roots can scarcely have any effect 
on them, and the only injury, and this is very slight, is probably due 
to a poisoning of the roots, perhaps by the beak of the 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 larve 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 was 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 birds 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 peri- 
odical Cicada, which, as we have already pointed out, is particularly 
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 larve and pupxe, when 
near the surface, are doubtless subject to the attacks of various 
predaceous coleopterous larve, and many of them are unquestionably 
destroyed by this agency. Upon leaving the ground to transform 
they present an attractive food for many insectivorous animals, and 
the pup and transforming adults are vigorously attacked by many 
