Parasites and Predators 



much to learn in such matters, established breeding 

 stations for the little beetles, and now, whenever or wherever 

 the cottony-cushion scale seems likely to gain the upper 

 hand, hosts of the beautiful little lady-birds are despatched, 

 to deal with the menace in their own way. 



Some of the other attempts to enlist the services of 

 predaceous insects have not been quite so happy. About 

 the time that the cottony-cushion scale was ravaging the 

 orange groves of California, a destructive moth, the gipsy- 

 moth, was introduced into the eastern states from Europe. 

 The larvae of this moth lost no time in stripping all the 

 trees bare of leaves, killing them wholesale and ruining 

 the crops of fruit. The net was spread far and wide in 

 the endeavour to find a saviour in the shape of an insect 

 friend. Could the story of the lady-bird be repeated in 

 this case? A large ground-beetle was selected for the 

 work. This ground-beetle is essentially predaceous. He 

 kills moths, their larvae and their pupae by severe nips 

 from his powerful jaws ; he chases his prey on the ground, 

 pursues them up trees, travelling to the very tips of the 

 branches when on hunting bent, and not only so, but his 

 larvae are equally bloodthirsty. 



The purple ground-beetle did not prove the success 

 against the gipsy-moth that had been anticipated. True, 

 he did his duty right manfully in the work of destruction, 

 but he did not increase sufficiently rapidly in the land of 

 his adoption to be of any real use ; moreover, in the event 

 of a temporary shortage in the supply of the gipsy-moths 

 which formed his food he would turn upon his fellows 

 and devour them. 



There are many other predators in the insect world : 

 dragon-flies, which prey upon insects smaller than them- 

 selves ; robber-flies, which will even hawk insects so large 

 and powerful as locusts ; hover-flies, which devour green-fly. 

 Amongst the birds and quadrupeds predators are every- 

 where to be found, 



From the very nature of their existence all parasites 



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