40 OUR HOUSEHOLD INSECTS 



for, besides these mandibular horns, there are two blunt 

 horns on the forehead, and the ridge that almost divides 

 the eyes is produced into a kind of flap or scoop on 

 each side. 



By these remarkable structures we are reminded of 

 what seems almost like a law in the insect world, viz., 

 that of all the different parts that make up the whole 

 organism of a typical insect there are some, such, for 

 example, as the legs, that preserve a very great uni- 

 formity of type throughout the class, varying in the 

 differen^ groups, and through the thousands upon thou- 

 sands of species, only within comparatively narrow limits, 

 while others seem possessed of much greater plasticity, 

 so to speak, and run off occasionally into such eccen- 

 tricities, extravagances, and apparent monstrosities, that 

 it seems as though there were no limit to the modifica- 

 tions of which they are capable. Perhaps the best 

 illustrations of this are to be found in the thorax and 

 antennae, in both of which most marvellous and unex- 

 pected developments, both in shape and size, are to be 

 met with. And in our present insect we see the head 

 and mandibles partaking of this same tendency to fan- 

 tastical modification, a tendency which, so far as man- 

 dibles are concerned, is manifested in a most remarkable 

 degree also in the stag-beetle, the " horns " of which are 

 really its jaws. And in that case, too, as in the present, 

 it is in the male sex that the structural peculiarity is 

 found. 



We conclude our notice of the family Tenebrionidce 

 with the creatures called " meal worms," which are the 

 larvae of two species of beetles, Tenebrio molitor and 

 T. obscurus. Both larvae and perfect insects are found 

 in granaries, flour-mills, and bakehouses, where they 



