PLANT LICE 



senses must be dull, indeed, if it is aphids that she wants. 



Do not lose sight of her, however, for her attitude has 



changed; now she certainly has her eye upon something 



that holds her attention, but the object is nothing other 



than one of those swollen parasitized aphids. Yet she 



excitedly runs up to it, feels it, grasps it, mounts upon 



it, examines it all over. Evidently she is satisfied. She 



dismounts, turns about, backs her abdomen against the 



inflated mummy; now 



out comes the swordlike 



ovipositor, and with a 



thrust it is sunken into 



the already parasitized 



aphid. Two minutes 



later her business is 



ended, the ovipositor is 



withdrawn, once more 



sheathed, and the insect 



is off and away. 



This tiny creature is a 

 hvperparasite, which is to 

 say, a parasite ot a para- 

 site. In the act just wit- 

 nessed she, too, has thrust 

 an egg into the aphid, 

 but the grub that will 

 hatch from it will devour 

 the parasitic occupant 

 that is already in pos- 

 session of the aphid's 

 skin. There are also parasites of hyperparasites, but the 

 series does not go on "ad infinitum" as in the old rhyme, 

 for the limitation of size must intervene. 



Fie. in. A parasitized Jarva of a lady- 

 bird beetle, and one of the parasites 

 The larva of the beetle has attached itself 

 to a leaf preparatory to pupation, but has 

 not changed to a pupa because of the 

 parasites within it. Above, one of the 

 parasites, which escaped from the beetle 

 larva through a hole it cut in the skin of 

 the latter 



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