DIRECT INJURIES CAUSED BY INSECTS. 105 



an abscess should be formed a . But the worst of all the 

 tick tribe is the American (Ixodes americanus] described 

 by Professor Kalm. This insect, which is related to 

 the preceding, is found in the woods of North America, 

 and is equally an enemy to man and beast. They are 

 there so infinitely numerous, that if you sit down upon 

 the ground, or upon the trunk of a tree, or walk with 

 naked feet or legs, they will cover you, and, plunging 

 their serrated rostrum into the bare places of the body, 

 begin to suck your blood, going deeper and deeper till 

 they are half buried in the flesh. Though at first they 

 occasion no uneasiness, when they have thus made good 

 their settlement, they produce an intolerable itching, fol- 

 lowed by acute pain and large tumours. It is now ex- 

 tremely difficult to extract them, the animal rather suf- 

 fering itself to be pulled to pieces than let go its hold ; 

 so that the rostrum and head being often left in the 

 wound, produce an inflammation and suppuration which 

 render it deep and dangerous. These ticks are at first 

 very small, sometimes scarcely visible, but by suction 

 will swell themselves out till they are as big as the end 

 of one's finger, when they often fall to the ground of 

 themselves 5 . The serrated haustellum of the ticks, which, 

 like the barbed sting of a bee, cannot be extracted un- 

 less the animal cooperates, is well worth your inspec- 

 tion ; and the species which infests our dogs is so common 

 that you will have no difficulty in procuring one for ex- 

 amination. 



I have now introduced you to the principal insects of 

 the Aptera order of Linne, which, in spite of all his care 

 and all his power, assail the lord of the creation, and 

 " Lesser L. ii. 222, note *. b De Geer, vii. 154-60. 



