252 OUR HOUSEHOLD INSECTS 



harm to cruciferous plants. The hind legs of the flea, 

 however, scarcely differ from the other pairs, except in 

 length, and the proportionate dimensions of all three 

 pairs are much the same, all having COXSB larger than 

 would be requisite for a walking insect. All parts of the 

 legs are beset with bristly hairs, those towards the end 

 of the tarsus being especially closely, packed. The ab- 

 dominal segments also are furnished with bands of long 

 stiff hairs across the back. No doubt these hairs all 

 pointing, as they do, away from the head aid the flea 

 quite as much as its compressed form in its endeavours 

 to insinuate itself into the small spaces between our 

 garments it has often to travel along in order to reach 

 its pastures ; and help, at the same time, to explain the 

 difficulty that one experiences in attempting to hold the 

 insect between finger and thumb. 



Turning now to the mouth organs (Fig. 78), we find a 

 far more complicated apparatus than might have been ex- 

 pected. The type of mouth 

 is that called suctorial, i.e., 

 it is adapted, as we are 

 painfully aware, for the 

 swallowing of liquid food, 

 obtained by a process of 

 perforation. In this respect 

 fleas agree with flies, and, 

 for the matter of that, with 

 bugs; but are totally un- 

 like bees, wasps, and ants, 



FIG. 78. Mouth Organs of Flea, s, to which group of insects 

 labrum ; mb, mandibles ; mx, max- -, , ,, , ,. 



mso;mp, maxillary palpi ;lp, labial Some people have thought 



they show some affinity. 



The labrum, or upper lip, seems to be represented only by 

 a slender saw-edged bristle, which is perforated throughout 



