LAEVA OF THE DYTICUS. 59 



but when it takes to flight, the alulets are exposed. These 

 Beetles have the power of producing a sort of humming sound, 

 some species louder than otliers, and it is generally thought 

 that the sound is produced by means of the alulets. 



Having now glanced at the history of the perfect Beetle, 

 we will turn to its larval existence. 



There is no possibility of evading the fact, that the larva of 

 the Dyticus is ugly. It is very ugly. It is the crocodile of 

 the insect world, lying unseen in its muddy bed, and darting- 

 out at any luckless insect that may pass near it. One of these 

 larvae is shown on Plate III. Fig. 4, as it appears when seizing- 

 its prey. 



When full grown, this larva is two inches in length. Its 

 colour is yellowish-brown, sometimes one tint predominating, 

 and sometimes the other. The reader will see how this sombre- 

 ness of hue enables it to lie concealed upon the mud as it waits 

 for prey. At the end of its body may be seen two slender 

 appendages fringed with hairs. These appendages commu- 

 nicate with the breathing tubes which pervade the body, and 

 the larva may be observed in a position resembling that which 

 is assumed by the perfect insect, the head downwards, and the 

 extremity of the tail just above the surface of the water, sus- 

 pended and balanced by the appendages. 



The mode in which this formidable creature obtains its 

 nourishment is very remarkable. The mandibles are, as may 

 be seen by reference to the plate, large, sharp, and curved. 

 When submitted to a good magnitier, they are seen to be con- 

 structed on the same principle as the fangs of a poisonous 

 serpent, a hollow groove running throughout their length. 

 This groove is not left open, but is closed for the greater part 

 of its length by a membrane, an aperture being left at the 

 base. This singular structure enables the larva first to plunge 

 its mandibles deeply into the body of its prey, and then to 

 suck out its juices though the hollow jaws. 



As is the case with the carnivorous Beetles generally, the 

 larva soon attains its full growth, and, when the time is at 

 hand for its change into tlie helpless pupal condition, it takes 

 itself to the bank, up which it climbs, and, burrowing into the 

 damp earth, forms for itself a sort of round cell or cocoon, 

 within which it assumes the pupal form. Should the change 



