45 
driven into the ground at intervals of 13 feet inches, slightly inclined 
towards the direction from which the attack of locusts is expected. A 
cord is stretched from stake to stake. The screens are tied to the in- 
side (locust side) of the stakes and to the cords by tapes. About 6 inches 
in width of the lower edge of the canvas is folded on the ground inside 
the stakes and weighted with earth. Pits are dug at intervals of gen- 
erally from 40 to 50 yards, and the usual size of the pits is 6 feet long ? 
2 feet 3 inches wide, and 3 feet deep. Round the edges of the pit is 
fixed the trap, consisting of four strips of zinc 9 inches wide. The 
screens having been so fixed as to head the advancing army of locusts, 
they march until their progress is stopped by the screen. They climb 
up the canvas until they reach the oilcloth, which they cannot pass. 
They 7 then descend and crawl to one side or the other until they fall into 
the pits, from which they attempt to escape by climbing up the sides 
until they encounter the zinc sheets which project 4 inches from the 
edge. They then fall back into the pit and when this is full to within 
about 9 inches of the brim earth is shoveled in to bury the locusts, a 
new pit having been excavated in the meanwhile to one side. The trap 
is removed to the new pit, and the same thing is repeated until the 
whole swarm has been destroyed. The use of this system has practi- 
cally rid Cyprus of the locust plague, and has also been of great avail 
in Algeria after other methods had failed. 
Coal Oil. — The use of coal oil and coal tar may best be considered in 
this connection, as both substances are employed in various ways for 
trapping and destroying the insects. As we shall presently see, in con- 
sidering the different available destructive agents, coal oil is the very 
best and cheapest that can be used against the locusts. It may be used 
in any of its cruder forms, and various contrivances have been employed 
to facilitate its practical application. The main idea embodied in these 
contrivances is that of a shallow receptacle of any convenient size (vary- 
iug from about 3 feet square to about 8 or 10 by 2 or 3 feet), provided 
with high back and sides, either mounted upon wheels or runners, or 
carried (by means of suitable handles or supporting rods) by hand. If 
the a pan" is larger than, say, 3 feet square, it is provided with trans- 
verse partitions which serve to prevent any slopping of the contents (in 
case water and oil are used), when the device is subjected to any sudden 
irregular motion, such as tipping, or in case of a wheeled pan, when it 
passes over uneven ground. The wheeled pan is pushed like a wheel- 
barrow ; the hand-worked pan is carried by long handles at its ends. On 
pushing or carrying, as the case may be, these pans, supplied with oil, 
over the infested fields, and manipulating the shafts or handles so as to 
elevate or depress the front edge of the pan as may be desired, the locusts 
are startled from their places and spring into the tar or oil, when they 
are either entangled by the tar and die slowly, or, coming in contact 
with the more active portion of the oil, expire almost immediately. In 
Colorado they use it to good advantage on the water in their irrigating 
