276 OUR HOUSEHOLD INSECTS 



first as a grub or maggot, next as a limbless motionless 

 chrysalis, and then as the perfect fly ; but the Hemiptera 

 or bugs pass through no such remarkable alterations 

 of form, and in their early life show a general resem- 

 blance to what they will ultimately become, differing 

 from the adult chiefly in size and depth of coloration, 

 and in the absence of wings and the immature condition 

 of the reproductive organs. Thus, while the young flea, 

 when hatched from the egg, is a wriggling, worm-like 

 creature, without limbs, and utterly unlike its parents, 

 the youngand newly hatched bug is a six-legged running 

 creature, to all intents and purposes a miniature repro- 

 duction of its parents, and a forecast of what it will 

 itself in a few weeks become. Hence fleas and bugs, 

 though alike in blood-sucking habits, and human para- 

 sitism, are yet at almost opposite poles in the series of 

 developmental types. 



In the form of the body, again, there is the strongest 

 possible contrast between these two parasites. Both are 



extremely narrow 

 in one direction, 

 and broad in an- 

 other; but in the 

 flea, the body is 

 extended vertically 

 and contracted 



FIG. 85. Diagrammatic Section of Body of laterally, and in 

 (A) Flea, and (B) Bed-Bug. J . . 



the bug it is ex- 

 tended laterally and contracted vertically ; the former is 

 compressed, the latter depressed. Fig. 85, representing 

 diagrammatically a vertical transverse section of the two 

 insects, strikingly shows this difference. The extremely 

 depressed and flattened form which the bed-bug exhibits 

 is by no means exceptional in the order Hemiptera ; in 



