156 PROCEEDINGS OP THIRTY-THIRD FRUIT-GROWERS ' CONVENTION. 



appears like magic. From this species I have reared two very efficient 

 parasites, and they also might be induced to take hold of our orchard 

 species. 



Here we have a new phase of insect parasitism before us. As I have 

 stated above, Corny s fusca, parasitic on three of our native Lecaniums, 

 took hold of the brown apricot scale, an imported pest, showing that 

 some species of parasites already in our State might, through trans- 

 porting, be made to attack some of the injurious pests of our orchards. 



In the Eastern States there are many species of parasitic and preda- 

 ceous insects which would be worthy of trial. This is especially true of 

 the aphis-eating ladybirds, of which we can never have too many 

 species. A complete record could be kept of localities where certain 

 parasites are known to exist and supplies of these could be collected 

 and distributed where they were most needed. One of the most 

 promising features of insect parasitism to-day is this very phase of the 

 work, the transportation of parasites from one locality to another. 

 From our wild mustard, which is attacked by a common aphis, which 

 in turn is attacked by a Braconid species, we have been able to gather 

 large quantities of aphis-infested material from which millions 

 of these Braconids were reared. These were taken to the melon fields 

 and liberated, where there was plenty of work awaiting them. The 

 growers claim that this work has saved their crop, which they valued 

 at $100,000. The same kind of work can be carried on with other para- 

 sites. Very often our native shrubbery has a severe outbreak of scale 

 or plant lice, and usually this is followed by a strong attack of parasites. 

 Here again, material could be gathered and parasites reared and dis- 

 tributed where most needed. These same Braconids have saved the 

 grain fields from destruction by the grain aphis (Toxoptera graninum), 

 and I may mention in this connection that in the Western States, this 

 last season, the grain crop was saved by the good work of these little 

 fellows. 



As an illustration of the work of some of our native parasites, I 

 might mention the oak-moth caterpillar (Phryganidia calif ornica) . 

 Those of you who live in the valley, where the live oak grows, espe- 

 cially in the bay counties, have observed the terrible destruction of the 

 oaks by this pest. Fortunately for the oaks, this attack does not occur 

 every year, and investigation has shown that the reason for this con- 

 dition is that three distinct parasites, Pimpla conquisitor, Chalets 

 ovata, and Hemiteles ashmeadii, as well as a true bug, a Pentatomid, 

 are keeping the pest in check. From a lot of pupae of this species which 

 I gathered in Santa Clara Valley, I reared 45 per cent of Chalets ovata, 

 besides a number of the other species. Yet, in off seasons, the prevalence 

 of the pest would warrant the establishment of more parasites or the 

 rearing and careful distribution of those mentioned above. 



