53 



of California are the only comnuinities in the Union that 

 pursue this policy of protection against foreign insect inva- 

 sion. One can hardly explain why it is that the Federal gov- 

 ernment discriminates against plant life. While all possible 

 precaution is taken by the U. S. Department of Agriculture 

 to prevent the introduction and spread of parasites affecting 

 man and his domestic animal, no such protection is extended 

 our useful plants. Federal control of insect pests already es- 

 tablished is now advocated. But why begin so late? Why 

 not attack the evil at the root and forestall the introduction of 

 foreign pests? 



INTENTIONAL INSECT IMPORTATIONS. 



During the past fourteen years the government of these Is- 

 lands was busily engaged in the importation of predacious and 

 parasitic insects, many of which are important enemies of 

 some of our citrus insect pests. It is difficult to say what the 

 fate of our citrus plants would have been without these, but 

 the trained eye readily sees the amount of help rendered us bv 

 these six-footed friends. 



CLASSIFICATION OF CITRUS INSECTS. 



Before proceeding with the description of the various insect 

 enemies of our citrus plants, it is advisable to acquaint the 

 reader with a skeleton of the scheme of classification of the 

 groups into which these insects fall. This grouping may be 

 viewed from either the standpoint of their structure or that 

 of the manner in which they do the injury. Generally speak- 

 ing, insects injure plants, depending upon the structure of 

 their mouth parts, either by biting portions of them, as do 

 Japanese beetles and various caterpillars, or by puncturing 

 the tissue and sucking up the sap. Arranging the insects ac- 

 cording to their structure, notice is taken of the kind of 

 months, i. e., whether sucking or biting, as well as the pres- 

 ence or absence of organs of locomotion — legs and wings — 

 the number and texture of the wings, the difference between 

 the sexes, etc. The economic importance of the nature of the 

 mouth and the bearing it has upon remedial measures will be 

 discussed later when remedies are considered. 



(To be continued.) 



