THE TRUE ARMY WORM AND ITS CONTROL. 11 
and cornfields where it is desired, if possible, to save the crop for 
forage purposes. 
_ MECHANICAL MEASURES. 
In case the worms are not discovered until they have begun to 
travel in a mass, they can usually be destroyed by furrowing or 
ditching (fig. 8) completely around the infested area. In attempt- 
ing to cross such ditches the worms will fall into them and can 
easily be destroyed by crushing them with a log dragged back and 
forth through the ditch or furrow. If shallow post holes are sunk 
in the bottom of the ditch at intervals of about 20 feet, the worms 
will crawl along the ditch bottoms and fall into the holes, where 
Fic. 8.—Ditch prepared to entrap marching army worms. A log, dragged back and 
forth through the ditch, crushes the worms which have falled into it. (Original.) 
they may be destroyed by crushing or other means. If the subsoil 
be of such a nature that water penetrates it but slowly, the post 
holes may be partially filled with water, on the top of which a layer 
of coal oil or petroleum may be poured. Upon falling into such 
holes, the worms are almost immediately destroyed without further 
action on the part of the farmer. 
SUMMARY OF CONTROL MEASURES. 
(1) Watch fields of growing grass and grain carefully, especially 
the meadows, during the spring and early summer months, in order 
