lU 



CALIFORNIA STATE COMMISSION OP HORTIC(^LTURE. 



of these aphis-infested leaves or twigs, place them in a small vial, and 

 cover it with gauze. In a short time you will find numbers of a tiny, 

 dark-colored insect, looking like a miniature wasp. This is a, Braconid 

 of the genus Aphidivs. There are millions of them at work; each one 

 eats an aphis, and afterwards lays hundreds of eggs on other aphids, 

 which, in their turn, eat up their hosts. These insects of the parasitic 

 class are usually small, and often so minute as to escape observation; 

 but insignificant as they appear, we owe our very existence to them, for 

 without their constant efforts we would be reduced to a condition of 

 starvation by the hordes of pests, which, having no checks, would 

 increase with enormous rapidity and soon overwhelm us like a fiood. 



The family Evaniidae is a small one, closely connected with the 

 Ichneumonidffi, but differing from them in structural characters. Its 

 habits are similar, as it is parasitic. 



The family Chaleididse is an immense group, composed largely, but 

 not wholly, of parasitic insects. As a rule, the members of this family 

 are exceedingly small, many of them being microscopic, and some even 

 requiring a high-power lens to bring them into view. Notwithstanding 



their minute size, however, they 

 ^ rank among the best friends the 



fruit-grower has, for they make up 

 in numbers what they lack in size, 

 i/';;^ and to the destructive pests of the 

 fruit-grower they are as "terrible 

 as an army with banners," for 

 within the ranks of the Chalcididti? 

 is comprised the largest number of 

 species of any of the parasitic 

 Hymenoptera, extending into many 

 thousands. The members of this 

 FIG. 111. Tonioccra caiifornica, a chaicid para- Order are Very Small, and, as a rule, 



site of black scale O'^aissetia ole^). Female, ^^^^ ^j_^g attractive bcauty of SOmC 

 very greatly enlarged. ■' 



of the larger insects, and so have 

 been much neglected by entomologists. Dr. L. 0. Howard, Chief of 

 the Bureau of Entomology of the United States Department of Agricul- 

 ture, has devoted much time to the study of this family, and to him, 

 more than to any one else, science is indebted for its knowledge of 

 this interesting and valuable group. Most of the species are parasitic, 

 and most of them confine their attacks to one class of insects. Some 

 of them, unfortunately, attack some of our beneficial insects, so that 

 they are not wholly beneficial from our viewpoint. 



In speaking of this family Professor Howard says: "Nowhere in 

 nature is there a more marked example of the co-relation between 



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