38 
As a natural sequence it follows that, although poisons are of value 
in many cases, we must place more reliance m preventives such as are 
to be found in cultural and mechanical methods. 
The arsenicals. — The insects can lie destroyed by different poisons. 
but too often such a course is apt to involve further injury or destruc- 
tion of the crop infested. Wherever the arsenicals. such as Paris 
green or London purple, can be used in the form of a spray without 
injury to the crop as food for cattle or for market, these are indicated. 
Certain persons have reported that Paris green and other insecticides 
employed were effectual in destroying the insects but also killed the 
plants affected. From experience with infested grasses which were 
under observation in the vicinity of Washington, we know that it is 
an easy matter to pass by the insect unrecognized and that the extent 
of the injury may also be unrecognized at the time when the insect's 
presence is quite obvious. It is quite probable, therefore, that the 
cases of reported injury attributed to insecticides were in reality due 
to the work of the insects themselves. 1 
Kerosene. — Lawns can be freed from the insects, at least in great 
measure, by the application of kerosene emulsion, followed with as 
copious a drenching as possible with water from a hose. It is per- 
haps needless to say that this remedy should not be employed in bright 
sunlight or on a hot day, but preferably toward sundown. 
The value of remedial applications was testified to by some of our 
correspondents, among whom was Mr. Charles Deering, of Chicago, 
who wrote, August 25, that kerosene, soap and water, and Paris green, 
were each effective in killing larvae near the surface, but when a water 
sprinkler was turned on. hundreds of active worms came up from the 
roots of the grass within an area of but a few feet. 
MECHANICAL METHODS OF DESTROYING THE 'SvORMS." 
V r arious mechanical and other measures have proved of value 
against the common army worm, and would prove effective against 
the fall army worm. In fields of young grain and on lawns many 
"worms" or larva? may be killed by rolling with a heavy roll, pref- 
erably when the insects are at work early in the morning or late in the 
afternoon, toward dusk. In pasture lands and in fields that are injured 
beyond recovery, sheep or other cattle could be turned in in numbers 
with benefit, as they will crush the larva? by trampling upon them. 
Other methods of this nature that are in use against the army 
worm proper, and that will be found of value, include trenching or 
1 In one case in particular there was no doubt whatever that the insects killed a plat 
of grass, although several of those who noticed the injury claimed that it was due to 
other causes. Had insecticides been applied these same persons, who, by the way, 
were not entomologists, would probably have claimed that the insecticides bad 
caused the death of the grass. 
