120 INTRODL'CTION TO ZOOLOGY. 



as in the preceding oraer. The female is furnished either 

 with a sting at the extremity of the abdomen, or with an 

 instrument termed an ovipositor {Fig. 107), used in the de- 

 position of the eggs. The jaws are powerful, and the tongue, 

 instead of being small and inconspicuous, becomes in some 

 tribes an organ of great size and importance. To this order 

 belong the Saw-flies, Gall-flies, Ants, Wasps, and Bees, 

 insects which have in all ages attracted attention, and among 

 which the power of instinct, in directing the actions of popu- 

 lous communities, is displayed in its highest perfection. 



The Saw-flies (TenthredinidcE, Fig. 104) tako. their name 

 from a pair of saw-like instruments, with which the female is 

 furnished, and which she employs for making an incision, in 

 which she deposits an egg. The tuiTiip, the rose, the apple, 

 and the -vvillow, suffer from insects of this tribe. But the 

 species best known in these countries, is perhaps that whose 

 larvae attack the gooseberry {Nematus grossvlarice). From 

 fifty to more than a thousand are sometimes observed upon a 

 smgle tree, of which they devour all the leaves at the begin- 

 ning of summer, so that the fruit cannot ripen. There are 

 two generations in the course of a year.* An allied species 

 attacks the red cuiTant ; but we have been infonned that it 

 sedulously avoids the black currant, and in the com'se of its 

 defoliating progi-ess leaves it quite untouched. 



The Gall-flies {Cgnipidce, Fig. 106) are those which 

 puncture plants, and, in the wound 

 thus made, insert one of their eggs 

 along Avith an irritating fluid, the action 

 of which upon the plant produces tu- 

 mours or galls of various sizes, shapes, 

 and colours. That found on the wild 

 rose, and called the beguar or bedeguar 

 of the rose, is well known, Tiie galls 

 which come to us from the Levant, and 

 which are of so much importance for 

 the manufacture of writing-ink and of 

 black dyes, are about the size of a boy's marble, and each 

 contains only one inhabitant; others support a number of 

 individuals. Mr. Westwood procured so large a number as 

 1 1 00 from one large gall found at the root of an oak. 



• Westwood's Introduction, voL ii. page 103* 



