Pests and Diseases 189 
abundant, control methods are necessary. One method 
of control is by plowing three or four furrows with the 
vertical edge facing the direction from which the army is 
approaching and dragging a log down these furrows to 
make a loose dust mulch. If the dust is warm, many of 
the insects perish by suffocation when they fall into this 
dust, but it is better to drag the pole down the furrow 
often during the invasion in order to kill as many as pos- 
sible. If the attack is severe, it is often a good policy to 
spray the furrows with kerosene emulsion in case there is 
not sufficient time to do the dragging. The best method 
of control consists in applying a heavy dose of lead ar- 
senate to the crop around the edge of the field. Poisoned 
bran mash is often effective in preventing a severe attack. 
By fall-plowing fields in which worms were numerous in 
late summer, many of the hibernating larvae are destroyed. 
The fall army-worm (Laphygma frugiperda S. and A.). 
This species is rather similar to the above insect, but 
its destructive period is usually later in the summer. In 
appearance it is very similar to the beet army-worm and 
is distinguished from it by the number of dots on its 
segments. It does not develop the army instinct so readily 
as the common army-worm and is not ordinarily so de- 
structive. It feeds on a wide variety of crops. Arsenical 
sprays are frequently successful in controlling this pest. 
Often on large fields, such as alfalfa stubble before the 
beet field is reached, many of the worms are crushed by 
running a heavy roller over the field. Plowing and 
disking, together with cultivation, kill many of the over- 
‘wintering forms. 
