172 
IOWA ACADEMY OP SCIENCES. 
mines are barely large enough to more than admit of the larva 
getting into them — in fact it requires considerable effort on the 
part of the larva to back out of one of these mines, when dis- 
turbed. 
It was found that some varieties of potatoes contained more 
pimples than other varieties. It was also found that varieties 
which did not contain many ‘\pimples” often contained as many 
“ slivers ” or tubes as the more “pimply” varieties. At the 
same time potatoes in all varieties could be found with “slivers” 
where no pimples had been formed. Whether “pimples” are 
formed only at certain stages of growth of the potato, or 
whether some varieties form “ pimples” while others do not, is 
still a question. 
CONTRIBUTIONS TO THE HEMIPTEROUS FAUNA 
OP IOWA. 
BY HERBERT OSBORN AND E. D. BALL, 
I. ON THE LIFE-HISTORY OP JASSID^. 
(With descriptions of new species and a review of the genus Deltccephalus.) 
In various papers published during the past five years the 
senior author has called attention to the injuries caused in grass 
lands and pastures by the numerous species of Jassidae, which 
swaim, often by millions to the acre, upon various species of 
grasses. 
In these papers it has been shown that the loss, though sel- 
dom noticed, must be really enormous, and that by the use of the 
tar pan or “hopper-dozer” the insects may be to a great extent 
destroyed. P urther than this, however, our knowledge has been 
too meager to furnish a certain basis for remedial measures. 
It is true studies were made of a few species and some facts 
learned as to their life-history which warranted the belief that 
burning, mowing, etc., might be of service, but still so much 
remained unknown regarding even the most common species, 
that there seemed a necessity for a more exhaustive study. At 
the beginning of the present season (1896) a study was planned, 
the essential features of which were: Pirs'u, a determination of 
the life histories of as many as possible of the species known to 
feed upon grasses. Second, the determination of the range of 
