34 
were not for the fact that during our latest tour of inspec- 
tion made to the infested part of southern Illinois (October 
5 to g) not a single field of corn was found anywhere, whatever 
may have been its situation or previous history, in which some 
trace of the disease could not be found among chinch bugs then 
remaining. It thus appears that conditions now are unusually 
favorable to an arrest next year of the prevailing chinch-bug 
outbreak, provided that the weather of the season is not too dry. 
Far more promising and important than the above was a 
series of experiments made by us on the Experiment Station 
farm July ro to 15, with methods for destroying chinch bugs as 
they leave infested fields of wheat at and shortly after harvest. 
By these experiments, thoroughly carried out under my own 
observation, I ascertained that chinch bugs can certainly be 
prevented at that season of the year from getting access to corn 
in any considerable number, and can be destroyed wholesale as 
they make the attempt to leave the wheat, at an expense far 
within the margin of economic operation. The method used 
was that which I have elsewhere characterized as the barrier 
method, the barrier in this case consisting of a strip of thoroughly 
pulverized earth with a deep, dusty furrow running through it, 
in the bottom of which, at intervals of about twenty feet, post- 
holes are sunk to a depth of a foot, or more. This makes a 
practically complete barrier and trap when the weather is dry, 
except that it requires the supervision of a man or boy for each 
eighty to one hundred and fifty rods. In wet weather a belt of 
coal-tar must be poured along the bottom of the furrow and 
renewed as may be necessary. 
OTHER ECOMOMIC INVESTIGATIONS. 
Impressed by the serious and growing damage to nursery 
stock in central Illinois, due to certain insects which infest the 
freshest leaves and the tips of the twigs, I began this year a series 
of systematic experiments with measures of prevention and 
remedy in the insectary and in the field, which I intend to carry 
forward year by year until a definite result is reached. Similar 
work on grass insects was also begun last fall and continued for 
a time this spring. A study of the scale insects of the State has 
been taken up by my assistant, Mr. W. G. Johnson, and meas- 
ures have been taken for a thorough investigation of insect 
