9 
ground between them a foot and a half across. The furrows w r ere 
two inches deep inside and five inches outside, the outer slopes 
varying from 40 to 54° 30'. 
We collected a quart and a gill of chinch-bugs (estimated number 
300,000) from adjacent corn, and placed them on the strip en¬ 
closed by the furrow T s, distributing them the whole length of the 
plot A few adults flew at once, and several others made the at¬ 
tempt, as, indeed, adults had occasionally done the day before. In 
tw r enty minutes probably nine tenths of them Avere dead upon the 
ground, evidently from the heat of the sun. Most of them had 
died on the hard earth between the furrow’s without reaching the 
latter. Two thirds of those in the furrows fit this time w T ere 
adults. Those dead from the heat were nearly all young, but an 
occasional adult was seen among them. 
The principal movement of the imprisoned chinch-bugs was at 
first to the north, into the furrow on that side, but presently they 
abandoned their attempt to scale this slope, and all remaining 
alive resorted to the south furrow, collecting chiefly at two points. 
This was evidently due to the greater heat of the north furrow 
on account of its more direct exposure to the sun. As the chinch- 
bugs work at a somew’hat steep slope they gradually undermine 
it, leaving an overhanging ledge wdiich they cannot scale, but 
which they gradually work down in their efforts to climb the bank. 
The temperature of the earth, determined by simply laying a 
thermometer on it in the sun, Avas 116° Fall, at 11:05. If the 
thermometer was barely buried in the dust it was 122°. The air 
temperature at the same time was 91°. Sky cloudless, and a gen¬ 
tle wind. 
To verify the effect of the hot earth and sun upon chinch-bugs, 
an additional pint was collected and put into the small enclosure 
used the preceding day. These Avere killed as above, and almost 
as rapidly. Wherever a rootlet or any other solid substance pro¬ 
jected above the surface it w 7 as thickly covered w T ith chinch-bugs, 
and a stick of any kind thrust in among them Avould be immedi¬ 
ately blackened by them, as they crawled upward, collecting at 
the top and dropping off as they crow’ded each other outAvard. 
Taking acWantage of this fact, a small trap Avas arranged by in¬ 
clining sticks OA 7 er a dipper of coal-tar. Two or three fluid ounces 
of chinch-bugs were collected in this way in the course of half 
an hour. This is, however, a very much less rapid method than 
the post-hole trap. 
We estimated that at the rate of action of the chinch-bugs in 
these furroAvs a single man could certainly supervise eighty rods 
along the edge of a field, and probably twice as great a distance. 
No. 3. July 12, a quantity of chinch-bugs Avas placed in the 
large enclosure described under experiment 2, the first lot at 6:25 
a. m. and a second at 7, and a coffee can w 7 as sunk in the fur- 
roAv at one end of the plot. 
At 7:40 chinch-bugs placed in the southern furrow, and a belt 
of coal-tar poured along the middle of the enclosed space. Day 
clear an 1 rather Avindy. At one place where the slope Avas 58 , 
