FISH-DESTROYING BUGS. 105 



one tarsal claw in the same place. It is not certainly known, 

 but it is likely that these insects reach their full growth in a 

 year. 



In seizing upon fishes or other small animals these insects 

 grasp their prey with their fore-feet, holding it firmly in their 

 claws, then piercing it with their beak or proboscis ; for they only 

 suck blood, not being able, as is the case with water-beetles, to 

 eat the whole animal. The proboscis consists of stout horny 

 setee or bristles, which fit closely together to form a fine sucking- 

 tube, while the exhaustion is performed by means of a muscular, 

 extensible pharynx, or throat. As is probably the case with all 

 carnivorous Hemiptera, only living prey is acceptable to these 

 insects. The predaceous water-bugs are said to destroy the 

 eggs of fishes, although further confirmation of this statement is 

 desirable. 



When the water-bugs attack other animals it is noticeable 

 that tlie prey dies much quicker than it would normally do, from 

 simply the loss of blood consequent upon the sucking of the 

 bug, so it is generally supposed that these insects inject a 

 poisonous secretion through their proboscis into the wound they 

 make. Most of tbese insects inflict severe stings in self-defence, 

 if they are handled too freely, using the proboscis for this 

 purpose. Leidy has described the salivary glands of Belostoma, 

 which are well developed (Journ. Acad. Nat. Sci. Philad. 1847, 

 p. 57), and it is the secretion of these glands that poisons the 

 prey when pierced by the proboscis. 



To destroy the bugs that attack fishes is not an easy matter. 

 The water-beetles can be trapped by the use of decaying 

 animal matter, of which they are very fond. I have seen a 

 dead rat in a small pond surrounded by a great number of these 

 beetles (Dytiscidas), and they prefer such food to living prey. 

 On the other hand, the water-bugs will take only living food, 

 so that their entrapping by any bait would be difficult. 



The use of poison for aquatic Hemiptera seems also impracti- 

 cable. Water-bugs are so much hardier than fish, that nothing 

 dissolved in the water would injure them that would not prove 

 dangerous for the fish.* 



* Abridged from the ' Annual Report of the Fish and Game Commis- 

 sioners of Massachusetts, 1886.' 



