SHEATH-WINGED INSECTS 



287 



the " mucro," which lies in a sheath. When the beetle falls over, it arches its body into the 

 form of a bow, resting only upon the head and the extreme tip of tlie abdomen, removes the 

 spine from its sheath, and then drives it sharply back again. The result is that the central 

 part of the body strikes the ground with such force that the insect springs into the air to a 

 height of 2 or 3 inches. Then, turning half over as it falls, it alights on its feet. 



The Fire-fly of the tropics belongs to the same group. The luminosity of this insect 

 proceeds from two different parts of the body, a brilliant yellowish-green light shining out 

 through two transparent window-like spots on the thora.x, while an orange glow is visible on 

 the lower surface of the abdomen. The e.xact cause of the light is unknown, as is also the 

 manner of its control by the 

 insect. 



The same may be said 

 of the common Glow-worm, 

 in which the light proceeds 

 from the lower surface of 

 the hind part of the body. 

 The male of this insect is 

 winged ; the female is grub- 

 like in appearance and wing- 

 less. The grub itself, which 

 may be found in autumn, is 

 also luminous, and feeds upon 

 snails. 



Another group includes 

 a very large number of beetles 

 of very varying character and 

 appearance. Among these are 

 the Oil-beetles, so called 

 from their habit of e.xuding 

 small drops of an oily liquid 

 from the joints of their limbs 

 when handled. The eggs are 

 laid in batches of several 

 thousand in holes in the 

 ground, and the little long- 

 legged grubs, on emerging, 

 clamberupthe stemsofflowers, 

 and hide themselves among 

 the petals to await the coming 

 of a bee. When one of the 

 latter appears, two or three of 



Fh0ii kj B. H. 4Vri,,,j 



IShtfiild 



COCKCHAFER ON DAISY 



A 'very dcitruct'tTe insect iL^hich feedi on the lea'ves of trees. The lar'va det'ours the roots 0* 

 plants., and is often so plentijul as to cause 'very serious mischtej 



the grubs cling to its hairy 



body, and are carried back to the nest, in which they live as parasites. One of these beetles 



may be seen commonly upon grassy banks in early spring. 



Allied to these insects is the Blistek-beetle, or Spanish Fly, so well known from its use 

 in medicine. It is a very handsome species, of a bright golden-green colour, occasionally 

 found in Great Britain on the foliage of ash-trees. In many parts of Southern Europe it is 

 extremely abundant. 



The beetles belonging to the large and important group of Weevils are characterised, as 

 a rule, by the fact that the head is prolonged into a more or less long and slender snout, 

 or " rostrum," at the end of which the jaws are situated. The number of species already 

 known is above 20,000. 



