CHAPTER XI 



CARNIVOROUS INSECTS 



Carnivorous insects may be divided into three groups, 

 viz.: — (1) insects of prey; (2) parasites; and (3) carrion 

 feeders or scavengers. By far the larger number of pre- 

 daceous species assail other insects, but a few feed upon 

 snails, earthworms, and similar small fry, while others 

 practice a kind of intermittent parasitism, and suck the 

 blood of large animals such as cattle and horses. Certain 

 insects attack and devour almost every creature of 

 appropriate size that they happen to encounter. In this 

 category we may include the tiger-beetles, the ground- 

 beetles, and some of the rove- beetles or cock-tails ; while 

 the carnivorous water-beetles are equally rapacious in 

 their own sphere of activity, the larger kinds actually 

 destroying young fish on occasion. Dragon-flies display 

 the same indiscriminate ferocity, first in their aquatic 

 larval state, and later when they become denizens of the 

 air. All these insects catch their prey by fair chase — if 

 we except dragon-fly nymphs, which are apt to lurk in 

 seclusion, and dart out their wonderful extensile jaws to 

 seize such small animals as may approach unawares. But 

 other species steal upon their victims, or wait patiently 

 in exposed situations until chance provides them with a 

 meal ; and in all these cases the insect cannot fail to reap 

 a double harvest from any resemblance to its surround- 

 ings with which it may be vested, for it will be equally 

 well hidden both from its enemies and from its prey. 



This principle of aggressive resemblance, as it is called, 



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