IOWA ACADEMY OP SCIENCES. 201 



latter, though perhaps having very little effcict as increasing 

 the actual quantity of timber, seems to me a much more impor- 

 tant factor in connection with the Cicada problem. These 

 insects show a very decided tendency to deposit their eggs in 

 young trees, and in 1871 and 1878 found abundant opportunity 

 in the numerous young orchards and groves developed since 

 their prior occurrence to satisfy this propensity, so much so 

 that they must have in many places deserted in no small degree 

 the natural timber areas for these artificial ones. 



Now, it seems natural to suppose that depending normally for 

 their food on roots common to areas of natural timber they 

 should have been met with a deficiency of such food in many 

 of the localities to which the adults had flown to deposit eggs, 

 and consequently have failed to develop and mature. 



Such an infiuenee will, of course, not be permanent and if 

 this be the only factor of importance Cicada should recuperate 

 in the future. 



It has been my privilege to observe personally the occur- 

 rences of both these broods since 1871, and I hope to have the 

 opportunity to observe many of their generations in the future. 



TIBICEN RIMOSA, SAY. 



This species, which may be considered as belonging more 

 particularly to the northern and western fauna, is represented 

 in this state by a depauperate form and in the northern and 

 western portions by a form more closely approaching the west- 

 ern type. 



It was described by Thomas Say in Proc. Acad. Nat. Sci. 

 for 1830, p. 235, who ascribes it to the Missouri and Arkansas 

 and says further ' ' Mr. Nuttall presented me with two specimens 

 which he obtained on the Missouri, and I found one on the 

 Arkansaw." 



While Mr. Nuttall's specimens may have been secured on 

 Iowa soil the probability seems strongly in favor of a location 

 further west in the then extensive territory of Missouri. 



But slight mention has been made of the species si«ce that 

 time and if it is found in the Mississippi valley as a species at 

 all common, it has failed to receive due mention. It is col- 

 lected in abundance in the Rocky Mountain region, and I have 

 numerous specimens from Colorado and New Mexico. 



Aside from the depauperate form to be mentioned further, 

 I have specimens from Tama county, collected by Mr. F. A. 



