jio 



ZOOLOGY 



HOW the 



was believed to have come from Australia. In Aus- 

 tralia, however, it was not destructive. It was sug- 



m Cabforma 



were saved gested that probably there existed in Australia one or 

 more natural enemies, which devoured it as fast as it 

 increased, and so kept it in check. It had reached 

 America without these enemies, and had been able to 

 multiply without hindrance. With some difficulty the 

 Government authorities were able to send a man to 

 Australia, on what must have seemed to many a wild- 

 goose chase ; but the result proved the correctness of 

 the a priori opinions. Natural enemies of the scale 

 were found in Australia and brought to America ; 

 and one of these in particular, a red lady-beetle, checked 

 the plague and soon reduced the pest to comparative 

 insignificance. Thus the "balance of nature," dis- 

 turbed by man, was restored. 



3. Quite a different sort of coccid is the San Jose 

 scale (Aspidiotus perniciosus). The Californian city of 

 San Jose (pronounced ho-say'} gives its name to this 

 notorious pest of orchard trees, but we now know that 

 it came from Asia. The scale is very small, hardly 

 larger than a pin's head, and is very hard to detect on 

 the bark of a tree, unless massed in quantity. Scales 

 of this type are therefore very easily carried about on 

 trees, and escape observation until they begin to appear 

 in the orchards as pests. On account of this, horti- 



San Jose 

 scale 



FIG. no. San Jose scale, showing the winged male form, a larva, and a mature 

 female with her protective scale ; all much enlarged. 



