alltUCTUUE OF INSECTS. 65 



is immediately under the root of the claw, has two 

 suckers appended to it by a narrow, funnel-shaped neck, 

 moveable by muscles in all direc- Fig. 54. 



tions. These suckers are shown in v 

 Fig. 54, which represent the under 

 side of the foot of the blue-bottle fly 

 (musca vomttoria), with the suckers 

 expanded. The sucking part of the 

 apparatus consists of a membrane ca- 

 pable of contraction and extension, 

 and the edges of which are serrated, 

 so as to fit them for the closest appli- 

 cations to any kind of surface. In the horse-fly, each 

 foot is furnished with three suckers. 



178. Mechanism in the Saw-Fly. In the yellow saw- 

 fly (cimbex lutea), there are four suckers, of which one 

 is placed upon the under surface of each of- the first joints 



Fig. 55- 



of the toes, Fig. 55. All the feet of this insect are thus 

 provided. Both of these figures are highly magnified. 



179. The mode in which these suckers operate may be 

 distinctly seen, by observing with a magnifying glass the 

 actions of a large blue-bottle fly in the inside of a glass 

 tumbler. A fly, by the application of this apparatus, 

 will remain suspended from the ceiling, with his back 

 downward, for any length of time, without the least 

 exertion ; for the weight of the body pulling against the 

 suckers, serves to make them adhere stronger, for the same 

 reason that a boy's leather sucker adheres more forcibly 

 in lifting a large stone than a small one. For this reason 

 it is, that house-flies prefer the ceiling to an upper surface 

 as a place of rest. 



In what manner is it said the house fly adheres to the under surfaces ot 



smooth bodies? 



6* 



