IOWA ACADEMY OP SCIENCES. 
201 
latter, though perhaps having very little effect 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 fiown to deposit eggs, 
and consequently have failed to develop and mature. 
Such an infiiience 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 since 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. P. A. 
