126 INSECTS. 



The antennae are said to be clavate when thickened at the extremity, in the form 

 of a knob or club ; lamellate when three or more of the terminal joints spread out 

 in broad processes which lie flat upon one another; serrate, when the joints have 

 on one side short angular processes like the teeth of a saw ; pectinate or comb-like, 

 when the processes are fairly long and stand out nearly at right angles; or 

 flabellate, if the processes are proportionately very long. These are some of the 

 chief types of antennae met with in the Coleoptera ; others of less frequent occur- 

 rence will be mentioned when we come to treat of the different families. The sense 

 of smell is undoubtedly very acute in a great many beetles, as anyone acquainted 

 with their habits could easily testify ; and it is considered probable that certain 

 minute pits scattered over the surface of the antennae, or crowded together on 

 special areas, are in some way connected with this sense. Though it is not so easy 

 to prove that beetles can hear, it seems hardly open to doubt that in some cases at 

 least they possess this faculty. Every one has heard of the death-watch beetle 

 (Anobium), which lives in old furniture and wood- work of houses, and makes a 

 noise like the ticking of a watch. This little beetle produces the noise by hammering 

 against the wood with its head, and apparently does so for the purpose of attracting 

 its mate, who replies by making a similar tapping sound. It is easy by imitating 

 their sounds to get the beetles to answer back ; so that here at least there is some 

 evidence that these insects are endowed with the faculty of hearing. Many other 

 beetles are able to make sounds, which though not nearly so intense as the chirping 

 of the crickets and grasshoppers, and not usually confined to one sex, are produced 

 somewhat after the same manner by the friction of one part of the body over 

 another. In beetles the sound sometimes arises from the rubbing of the hind-legs 

 against the edge of the elytra, but in most cases it results from the rubbing of an 

 edge over an adjacent area which is crossed like a file by a number of fine parallel 

 ridges. This stridulating area is in some beetles placed on the upper side of the 

 back part of the head, or on the gular surface underneath, so that when the head 

 moves in its socket the upper or lower edge of the prothorax, as the case may be, 

 scrapes along the file and thus gives rise to the sound. The prothorax of beetles 

 is, as we have already stated, freely articulated with the mesothorax. Its dorsal 

 arch or pronotum ordinarily covers over the whole of the mesonotum, with the 

 exception of the small piece known as the scutellum ; but when the prothorax is 

 bent down, a considerable part of the mesonotum in front of the scutellurn comes 

 into view. It is on this part that the stridulating area of most of the longicorns 

 and of some phytophagous beetles (Megalopince) is situated. These insects make a 

 sort of squeaking noise which is sometimes fairly loud by rapidly bending the 

 prothorax up and down, and so causing its hind edge to move backwards and 

 forwards over the ribbed surface of the mesonotum. In other beetles the stridu- 

 lating area may be either on the upper surface of one of the hinder segments of 

 the abdomen, or on the sides of one of the anterior segments ; the sound being 

 produced in the one case by the friction of the area against the edge of the elytra, 

 in the other by that of the posterior thighs against the sides of the abdomen. 



Beetles are among the most active of insects when on the ground, and, in accord- 

 ance with their running powers, we find that their legs, though generally slender, are 

 strong and well developed. But in certain groups, where the habits and environ- 



