REMEDIAL AND PREVENTIVE MEASURES. 59 
THE RIDGE AND COAL TAR METHOD. 
Differing quite materially from the preceding are the various com- 
binations of coal tar and ridges of earth, smoothed and packed along 
the apex, or, instead of the ridge of earth, 6-inch boards, such as 
are ordinarily used for fencing, placed on edge and the upper edge 
coated with tar. Forbes has reported excellent results from the appli- 
cation of a line of coal tar put directly upon the bare ground where the 
surface has been rendered compact by a recent fall of rain. Even in 
this series of protective measures kerosene can be used to great 
advantage. In the experiment recorded by Professor Forbes the coal 
tar was put upon the ground between a wheat field and a corn field 
from an ordinary garden sprinkling pot from which the sprinkler had 
been removed and the orifice of the spout reduced in size with a plug 
of wood until the tar came out in a stream about the size of the little 
finger and made a line on the surface of the ground about three-fourths 
of an inch in width. Post holes were sunk along the line from 10 to 
20 feet apart on the side next to the wheat field, thus practically com- 
pleting the barrier, and the chinch bugs being unable to cross the line 
of tar accumulated in the post holes in vast numbers, where they were 
killed, and those bugs that had already entered the cornfield before 
the barrier was constructed were prevented from spreading further by 
tar lines between the rows of corn, the infested corn itself being cleared 
of bugs by the application of kerosene emulsion. The same writer 
states* that several farmers in Vermilion County, 111., prepared for the 
coaltar line by hitching a team to a heavy plank and running this, 
weighted down with three or four men, over the ground once or twice 
until a smooth, hard surface had thus been made to receive the tar. 
If the barrier was to be made in sod, a furrow was plowed and the 
bottom of this made smooth by dragging the plank along the bottom. 
In both cases post holes were sunk along the tar lines, and in these 
were placed cans or ws into which the bugs fell in myriads and were 
destroyed. 
On one farm of 250 acres a coal-tar line 00 rods in length was renewed 
once each day and killed about 8 gallons of chinch bugs. In the case 
of another farmer there were 300 rods of tar lines with post holes, cans, 
etc., which resulted in destroying about 10 bushels of chinch bugs. 
A 6-gallon jarful was destroyed in less than half a day at one point 
on the line. In this last instance the lines of tar were renewed three 
times a day, but even then less than a barrel of tar was used. Still 
another farmer, with 120 rods of tar line, used about a third of a barrel 
of tar and did not lose a hill of corn; he caught chinch bugs by the 
bushel. In some of the cases cited the tar line was run in a zigzag 
course, the post holes being situated at the angles, and in others leader 
tar lines were run obliquely to the main tar line, one end terminating 
* Twentieth Report oi' State Entomologist of Illinois, i>. 39, 1898. 
