36 



THAT S IT ; 



of insects is a, yellowish semi-trans- 

 parent fluid. They have a com- 

 plete system of digestive organs, 

 consisting, in some classes, of 

 mandibles 13, gullet 14, crop 15 

 r/izzard 16, stomach 17, biliary 

 vessels (taking the place of a 

 liver) 18, intestines 19, secretory 

 glands 20. But as the habits, 

 forms, and food of insects vary 

 in a remarkable degree, their in- 

 ternal organizations are marked 

 by great modifications. 



Insects have nervous systems, 

 consisting of numerous ganglia, 

 1, 2, 3, 4, and 

 nerves of special 

 sense, as the op- 

 tic nerves, 5. The 

 muscles, 6, of in- 

 sects are very 

 numerous, and, 

 relatively to their 

 size, of enormous 

 strength. The 

 muscles of flight, 

 7, are capable of the most strenu 



produce the peculiar noise for 

 which it is remarkable, by rub- 

 bing its palpi, 8, against the^ro- 

 boscis, 9. Crickets, grass-hoppers, 



205. 



locusts, and tree-hoppers, pro- 

 duce their chirrup by rubbing 

 the dentated parts of their thighs 

 against their wing-cases ; but they 

 have a sort of drum on each cide 

 of the first segment of the abdo- 

 men, 10. There are two outer 

 drums, 11, two inner drums, 12, 

 and a group of muscular bands, 

 13, which are connected with the 

 production of sounds. The death- 

 watch (Anobium tesselatum), 14, 

 produces a ticking noise by the 

 mechanical action of striking its 

 bead against wood-work. Other 

 insects produce sounds by gnaw- 



15 ing wood, by 

 snapping their 

 mandibles, or by 



|— striking with 

 1§8 * nen * abdomen. 



^^pp insects to man 



16 are various. The 

 206 « bee (Apis melli- 



ous action, and of long endurance. 



The sounds produced by in- 

 sects are caused in various ways. , 



House-flies, bees, wasps, etc. ; \jlca), 15, yields wax and honey, 16 

 have vocal spiracles behind their 1 «how doth the little busy bee 

 wings, by which they cause 

 jets of air to impinge upon the 

 edges of their wings. The death's- j 

 head hawk-moth (Acherontia j 

 atropos) has been supposed to j 



Improve each shining hour, 

 And gather honey all the day, 

 From every opening flower. 



"How skilfully *-he builds her cell. 

 How neatly spreads her wax ; 

 And labours hard to store it \\ ell, 

 With the sweet food she makes/* 



