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 leap 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 auletes 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 tibicen of Linnaeus, also from New 

 York, and quite common even within the city; and the hieroglyphica of Say, 

 which, I 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. pruinosa, 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. UIILEU.] 



