Tower-Building Cicada. 



101 



DOME-LIKE HOUSE OF CICADA. 

 Longitudinal Section Showing Pupa in Two Positions. 



some days in advance of the females, and also disappear 

 sooner. During several successive nights the pupae con- 

 tinue to issue from the ground, and in some places, as was 

 the case in May of 1868, when these insects appeared in 

 great numbers in the vicinity of Philadelphia, the whole sur- 

 face of the soil was made by their operations to assume a 

 honey-combed appearance. 



In localities where the soil is low and swampy, a remark- 

 able chamber is built up by the larva, where the pupa may 

 be found awaiting the time of its change to the winged state. 

 These chambers were first noticed by S. S. Rathvon, at Lan- 

 caster, Pa., and are from four to six inches above the ground, 

 and have a diameter of one inch and a quarter. When 

 ready to emerge the insect backs down to an opening which 

 is left in the side of the structure on a level with the surface 

 of the ground, issues forth and undergoes its transformation 

 in the usual manner. This peculiar habit of nest-building, 

 which is so unlike what is customary with the Cicadidae, or 

 with Hemiptera in general, points to a high degree of intelli- 

 gence among these insects, showing a remarkable ability to 

 adapt themselves to environing circumstances. Undue 

 moisture would be prejudicial to the pupa, as the larva 



