CARNIVOROUS INSECTS 177 



bugs are the common back-swimmer or water boatman 

 (Notonecta glauca) and the water scorpion {Nepa cinerea)- 

 The latter is one of the commonest British insects. It 

 frequents shallow, stagnant water, and usually lies hidden 

 in the mud ; but even when it creeps sluggishly among 

 the weeds, it is rendered inconspicuous by its flattened 

 form and miry guise. Its raptorial fore-legs enable it to 

 play the part of an aquatic mantid by seizing any smaller 

 insect that comes within its reach ; but the resemblance 

 ends here, for while the mantid tears its victim in pieces, 

 the water scorpion must needs suck its juices. The water 

 boatman, thanks to its oar-like hind-legs, is a very active 

 insect, and catches its prey by sheer speed and agility. It 

 feeds upon small aquatic creatures, including tadpoles, 

 and is strong enough to master a good-sized minnow. A 

 chance prick from its sucking beak proves to be almost as 

 painful as a bee's sting. Indeed, like many other species, 

 it pours a poisonous saliva into the wound which it makes, 

 thus paralysing or killing its victim. 



So far as is known, the curious scorpion-flies, which 

 make up the order Mecoptera, are exclusively predatory, 

 though their caterpillar-like larvae are believed to feed for 

 the most part upon dead animal matter. The adults, 

 which are especially characteristic of woodland districts, 

 capture other insects. A European species (Bittacus 

 tipularius) has unusually long limbs, and resembles a 

 "daddy-longlegs" or crane-fly. It preys upon flies, and 

 when feeding is said to hold its victim with its hind-legs — 

 the other two pairs being used to suspend itself from the 

 steins of grasses. 



Many carnivorous insects are very partial in their 

 choice of food ; and we find whole groups of families, 

 scattered throughout the orders, which agree in their 

 fidelity to a particular diet. Aphides, for example, are 



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