Insects 167 



They are, in fact, among the most dangerous of all insects, and 

 very large amounts of money are annually spent in destroying 

 them, or in the effort to prevent their further spread. After this 

 statement, it may sound alarming to say that there are numerous 

 species native in Colorado, but actually these native species rarely 

 do any serious damage. The introduced kinds, accidentally 

 brought in on plants, are the ones which ruin the orchards. These 

 are the species which specially feed on our cultivated trees, and 

 which, away from their native home, are also away from most 

 of the natural enemies which would keep them in check. In 1908 

 Mr. T. B. Holman brought me some twigs from a Japanese quince 

 received at Boulder, but not yet planted out. Microscopic ex- 

 amination showed that they were infested by the San Jose Scale 

 (Aspidiotus perniciosus of Comstock). This scale is really a 

 native of Asia, but it was accidentally introduced into California, 

 and was first noticed at San Jose, whence the popular name. It 

 has spread right across the country, on deciduous fruit trees, 

 doing enormous damage. An infested orchard shows dead and 

 dying trees, which seem to be covered with a sort of gray scurf. 

 Thus it will be understood that the keen eyes of the inspector, 

 detecting the pest before the imported trees were planted, saved 

 the orchardists tribulation and expense, to a greater extent than 

 most of them realize. Some years ago I received a piece of twig 

 from a correspondent in Argentina, with a letter asking the name 

 of the scales infesting it; they were new to Argentina. The insect 

 was the San Jose Scale, and I hastened to write urging that every 

 effort should be made to prevent the spread of such a pest. When 

 recently in that country I learned that it had spread far and wide, 

 and was now considered one of the permanent enemies of the 

 fruit grower. So far, we are more fortunate in the vicinity of 

 Boulder. 



The more highly specialized scale insects, such as the San 

 Jose scale, seem to contradict the definition of an insect, and also 

 that of the order Hemiptera, to which they belong. The adult 

 females are without legs and practically without antennae, 

 though they have large mouth-parts, adapted for sucking the sap 

 out of the trees. The adult males, which last only a short time 

 and are rarely seen, are totally different. They are small fragile 

 creatures with a single pair of wings, six legs and long antennae, 





