68 HALF HOURS WITH INSECTS. [Packard. 



distinguish them apart, as an enemy of our comfort or 

 crops. 



Moreover there are Insects which are friendly in but a Piclv- 

 wickian sense. There are certain parasitic insects that sticlv 

 to us closer than a brother, and yet with the moral qualities 

 of fiends. Man is a sort of treasury or bank to these crea- 

 tures — and they are happily few in number — who "draw" 

 upon him not only " at sight," but who " go it blind." And 

 when through carelessness or idleness the bank is too attrac- 

 tive and liberal in its discounts, the audacious vermin congre- 

 gate in teeming hosts, and make "a run" upon it. Parasitic 

 insects seem in many cases to be actually blind through ava- 

 rice, as amaurosis is not an uncommon affection 

 Fig. 54. 



among articulated parasites. It would seem as 



if the gods struck blind all such beings for their 

 greed in sucking our blood. 



There is the louse (Fig. 54), the most intimate 

 of these friends, forsooth, of ours. Ugly and 

 repulsive in itself, it is tenfold more so in its 

 associations. Though its legs are well devel- 

 oped, the beak wonderfully adapted for its use, 



vet it lives in a Stygian twilight, its eyes re- 

 Louse. -^ - , . 



duced to a simple pomt, a little depression on 



the side of its head forming but a single isolated facet, the 



simplest kind of eye, when there are 25,088 such facets in 



the eye of a certain small beetle (Mordella) and 4000 in 



that of the house fly, whose head is all eyes. If we look 



at the beak of the louse (Fig. 55) we shall at once perceive 



that the creature does not bite, but that it in reality sucks 



onr blood ; so the mosquito introduces its blade-like jaws 



and sucks our blood. It is incorrect to say that a mosquito 



bites. Those organs that in allied insects are jaws, in the 



lice lose their biting function and are converted into a fleshy 



extensible tube, the true jaws forming ribbon-like bands 



strengthening the tube. 



4 



