Parasites and Predators 



little creature, doing yeoman service in ridding our gardens 

 of the obnoxious green-fly. It is, however, of an Australian 

 and not of a British lady-bird that we would speak, a little 

 creature that formed the central figure in one of the 

 greatest romances of the insect world. We will relate the 

 story from the beginning. 



In the year 1868 a scale insect, known as the cottony- 

 cushion scale, was introduced into the United States from 

 Australia. Now there is no family of insects more 

 destructive than the scale insects. Two of them only are 

 of use to man : the cochineal insect, from which a dye is 

 prepared, and the lac insect, from which shellac is obtained. 

 A large family with only two reputable members is indeed 

 in bad case. 



Most of the scale insects have the obnoxious habit 

 of driving their awl-like beaks into plant tissues and 

 sucking out their juices ; at the same time they cover 

 themselves with hard and horny cases, whence they derive 

 their name. Well, as we have said, a number of these 

 insects reached America about fifty years ago. It so 

 happened that these particular insects were very 

 destructive to citrus plants and, of course, they found their 

 way to^ the citrus groves of California. Here they did 

 enormous damage, and all the efforts of the orange and 

 lemon growers to keep them in check proved of no avail. 

 The Americans, therefore, sent an entomologist to 

 Australia with the object of discovering how it happened 

 that this scale insect was not particularly destructive in 

 its native home. 



Success met this scientist. He found that everywhere 

 in Australia the scale was devoured by a little red lady- 

 bird and its larvae. Some of these beetles were sent home, 

 but they died on the voyage. A second shipment was 

 more fortunate, and the little aliens bred and multiplied 

 in the land of their adoption to such an extent that the 

 cottony-cushion scale is now no longer a pest in California. 

 The wise American government, from which our own has 



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