THE HARVEST-FLIES. 
219 
that the females of the dog-day harvest-fly prefer to lay their 
eggs in one rather than in another kind of tree ; for I have 
taken the pupae emerging from the ground beneath cherry, 
maple, and elm trees, and it is probable that they could not 
have travelled far from the trees upon which, when young, 
they were hatched, and upon the trunks of which they finally 
leave their vacant shells. These have much the same form 
and appearance as the pupa-shells of the seventeen-year har- 
vest-fly, but are considerably larger. Some individuals of 
this species continue with us as late as the end of September. 
As they are not very numerous, the injury sustained by the 
trees from their punctures is comparatively small. 
The other harvest-flies of this country have only two eye- 
lets, and are not furnished with musical instruments ; but 
they enjoy the faculty of leaping, which the Cicadas do not. 
This faculty does not, as in the grasshoppers and other leap- 
ing insects, result from an enlargement of their hindmost 
thighs, which do not differ much in thickness from the 
others ; but is owing to the length of their hindmost shanks, 
or to the bristles and spines with which these parts are 
clothed and tipped. These spines serve to fix the hind 
legs securely to the surface, and, when the insect suddenly 
unbends its legs, its body is launched forward in the air. 
Some of these harvest-flies, when assisted by their wings, 
will leaj) to the distance of five or six feet, which is more 
than two hundred and fifty times their own length ; in the 
serve to distinguish them from each other. 2 In my collection are four more na- 
tive species of Cicada; namely, the aulctes of Germar, our largest species, from 
North Carolina; a second species, apparently undescribed, about equal to this in 
magnitude, from Long Island, New York; the tibiccn of Linnaeus, also from New 
York, and quite common even within the city; and the hieroglyphica of Say, 
which, 1 believe, was captured in Florida, and was presented to me by Mr. Ed- 
ward Doubleday. A specimen of the tibicen, or some other large species, has been 
taken in Massachusetts, but I have not the individual to refer to at this time. 
[ 2 This is nothing more than a local variety of C. pminosa , Say; there is no 
persistency in the form and length of the abdominal valves, and the coloration 
and extent of pruinoseness upon the insect depend upon various contingencies to 
which it is liable. — Uhusr.] 
