6 
ENTOMOLOGICAL WORK OF THE YEAR. 
The long continuation of the incursions of the destructive Rocky 
Mountain Locusts into the border States of the West having caused 
great alarm and uneasiness in these States, an investigation into the 
history and habits of these insects was determined upon in order to 
see if any means of counteracting them could be devised. I felt sat¬ 
isfied from wffiat was already known in reference to them that there 
was no real danger of their penetrating into Illinois ; but, as many of 
our citizens, especially in the northwestern part of the State, not¬ 
withstanding the assurances I had given, still apprehended danger, I 
concluded to assist in the investigation, with special reference, so far 
as our State is concerned, as to the probability of their incursions 
being extended to the country east of the Mississippi. The result of 
the past year has triumphantly vindicated my prediction, and has 
proved the correctness of the theory first advanced by Mr. Walsh, our 
first State Entomologist, that the middle of Iowa was and would con¬ 
tinue to be the eastern limit of their range. The eastern limit of 
their range as indicated by him as early as 1866, and subsequently 
more definitely mapped by Prof. Riley, proved to be the limit of their 
movements eastward in 1877. This limit, as definitely ascertained 
by the United States Entomological Commission, is about as follows: 
Commencing at the south end of Lake Winnipeg, in British America, 
the line runs southeast to the Lake of the Woods, thence south by 
way of St. Paul, Minnesota, to Pierce county, Wisconsin; thence 
almost directly south to Poweshiek county, Iowa; thence southwest 
to Worth county, Missouri, through which State it passes in an 
almost south direction to the extreme northwest corner of Arkansas; 
thence south to Houston in Texas. As this line has not been crossed 
in the past twenty years, it is reasonable to conclude that so long as 
the climatic conditions of the northwest remain the same as at pres¬ 
ent it will form the eastern limit of their movements.^ 
This investigation necessarily required me to be absent from the 
State occasionally during the Summer ; therefore, in order that obser¬ 
vations in reference to insects found in our own State might not be 
neglected, in addition to Miss Nettie Middleton, who has from the 
first been my office assistant, I employed Prof. G. H. French, of Irving¬ 
ton, as general assistant, and Miss Emma A. Smith, of Peoria, as 
special assistant for the northwest part of the State. The work done 
by the latter two will be shown by their respective papers contained 
in this report, and by what is hereafter stated. 
I think I can say truly and without undue boasting, that more 
work has been done during the year which has just closed, in refer¬ 
ence to Economic Entomology in Illinois, than was ever done before 
in a single year. 
As more useful work can be done in Natural History by directing 
attention to specific subjects than in any other way, we adopted this 
method during the past season. 
I continued my investigations of the Plant-lice (Aphidss), having 
published a preliminary paper on them in the Transactions of the 
* I propose, during 1878, to investigate the climatic condition of the Northwest with reference to 
this subject, if I can find time. 
