44 
oil and nine tenths coal-tar was so sticky after 72 hours that 
chinch bugs could not cross it, and even at the end of 96 hours 
still served its purpose. Mixtures of one fifth oil with coal-tar, 
and of equal parts of each, were found much less satisfactory. 
Diluted with one tenth oil, tar is too fluid to use upon the ground, 
as it speedily soaks in; and consequently if this mixture be used,, 
boards must be placed around the field either set on edge or, pref¬ 
erably, laid flat, a little strip of ground having been first prepared 
so that they may be sufficiently bedded in the earth to keep the 
bugs from passing beneath them. 
As a more convenient and effective means of maintaining a coal- 
tar barrier, I suggest that strips of sheet iron bent at the top to 
form a gutter about one inch across and half an inch in depth at 
the middle, be placed end to end, slightly overlapping, the tar to 
be poured in this gutter. If necessary to prevent too free an 
escape at the joints, it may be slightly thickened by stirring in 
dust. Small pits sunk at intervals along a barrier of this descrip¬ 
tion would gather the chinch bugs in great numbers, where they 
could be readily killed with a little kerosene and water, or by 
mechanical methods. 
STARVATION EXPERIMENTS. 
To ascertain how long the chinch bug in its different stages- 
may live without feeding (a point applying to several field methods 
of contest with this insect) we confined, September 4, under a 
bell jar. without food, a miscellaneous lot of bugs of various ages, 
from the very young of the first stage to adults more than a week 
old. In twenty-four hours a few of the youngest were dead, and 
in twenty-eight hours, one adult. In forty-eight hours a number 
of adults, larvae, and pupae, were dead, and September 7, many 
more of the last, and almost all the larvae. September 8, only a 
very few adults and a few pupae remained; September 9 five 
adults were still living, all the others dead; and September 10, , 
six days after beginning, all were dead but one adult. 
This experiment is open to the objection that the bugs were on 
a table in the office, and the dryness of the air may have had 
much to do with their death; and as no check lot was separated, 
it is impossible to say that these specimens were not suffering 
from one of the diseases prevalent at the time in the region from 
which they came. 
In an experiment begun August 13, with young bugs, taken as 
fast as they hatched from the egg and confined without food, none 
lived twenty-four hours, but most died within twelve. These eggs 
began to hatch when fifteen days old. 
A variation in this experiment consisted in burying lots of 
chinch bugs at the depth practicable by plowing, and examining 
at intervals to determine their condition. 
August 13, two lots of larvae and pupae were buried two inches 
deep, one with food and one without. Forty-eight hours after¬ 
ward both were uncovered and found uninjured, and seventy-two 
