202 SPAN-WORMS. 
sticky application so as to make it an effectual barrier to 
the ascent of the insect, still it will pay, wherever the canker- 
worm abounds, to give this matter the attention requisite 
to insure success. The limited power of motion possessed 
by the female usually confines this insect within narrow 
limits, and hence it is local in its attacks, sometimes abound- 
ing in one orchard and being scarcely known in a neighbor- 
ing one; but when it has obtained a footing, and is neg- 
lected, it usually multiplies prodigiously. Strong winds will 
sometimes carry the larve from one tree to another near by. 
When the caterpillars are once on a tree, if the tree is small, 
they may be dislodged by jarring, when they all drop sus- 
pended in mid-air by silken threads; then by swinging a 
stick above them the threads may be collected and the larve 
brought to the ground and destroyed. Fall plowing has 
been recommended to destroy the chrysalids by turning 
them up, when they are likely to be either killed by exposure 
or devoured by birds. Hogs also are very useful in destroy- 
ing this pest by rooting up the chrysalids and eating them.”’ 
The use of ‘‘Raupenleim"’ has given very good results, and 
as this material remains sticky for a long time it is better 
than simple tar, etc. 
Canker-worms have many enemies which assist us 
greatly to keep them in check. The eggs are devoured by a 
small red-mite, and a very small wasp finds the minute eggs 
large enough to furnish food for her offspring, hence she de- 
posits her eggs into the larger ones of the canker-moths. 
The caterpillars themselves are preyed upon by larger para- 
sitic wasps and flies, and predacious insects also feed upon 
them in large numbers. One of our Caterpillar-hunters 
(Calosoma frigida Fig. 145), a large black and active beetle, 
is found in large numbers in Minnesota wherever canker- 
worms have greatly increased in numbers, and they make 
war upon them day and night. These beetles are just as 
active as their green relatives farther south, and climb with 
equal facility. It is amusing to see them running over the 
