Packard] 



INSECTS OF tup: GARDEN. 



41 



species, are greatly iucroascd. We know from personal ob- 

 servation that these male scale insects do travel far from the 

 trees on which their partners occnr. 



This leads us to regard this almost unnatural activit}' of 

 the male scale insect as tending to prevent too close in-and-in 

 breeding in the species. Nature in her wise and prudent 

 forethought thus, instead of confining the sexes to one tree, 

 so that cousins intermarry and the stock deteriorates, scat- 



FiG. 32. 



Pine Scale Insect. 



ters these two-winged atoms, bearing them along on the wings 

 of the wind and landing them in other groves and orchards, 

 where they ma}^ intermarry with different races, and tlius the 

 species be restrained within the proi)er limits. Here wc have 

 another cause by which these sexual differences may have 

 been produced. 



Any one who has noticed these female scale insects clus- 

 tering on an orange or iv}^ or oleander leaf, knows how much 

 their form varies with that of the surface to which they are 



9 



