134 NATURAL HISTORY. 



lines long, one in thickness ; altogether green ; the wings 

 long, transparent, and veined with green ; the straight 

 and pointed horn on the forehead, prolonged into a muz- 

 zle, has three ridges above and five below ; the abdomen 

 is large, resembling that of the house-fly, ending in a 

 forked point. Found in the south, but not unfrequently 

 as far north as Germany. 



The Leaf Louse (aphis) is a little round insect, which 

 is sometimes provided with wings and tubes, which, situ- 

 ated in the posterior part of the body, are fitted for the 

 reception of honey. The aphidse are more sluggish than any 

 others of the Parasita, and are found by thousands, clus- 

 tering on the juicy stalks of different plants, which they 

 injure by piercing the twig with their sharp sting and 

 sucking the sap. They are variously colored, some are 

 green, some brown, others black, and their increase is 

 rapid and immense, almost beyond belief. It is remark- 

 able that the males, which are winged, only appear in 

 autumn. The females form the large societies found 

 clustering together. Some produce living young, others 

 lay eggs. Their increase is wonderful ; one individual, 

 it is said, will produce twenty broods in one summer, 

 and as every five generations number six millions, it may 

 be supposed what devastation such numbers would cause 

 in a garden, if they were not destroyed by other insects. 

 The ants pursue and feed on them for the sake of the 

 transparent saccharine fluid, termed honey dew, which 

 exudes from their bodies. One species, which lives on 

 pines, by puncturing a vulnerable part, produce monstros- 

 ities, having the appearance of galls, within which both 

 insect and larvae dwell. 



The Leaf Fleas (chermes), called also by the French 

 False Plant Lice, are very small insects, resembling 



