PROCEEDINGS OF THIRTY-THIRD FRUIT-GROWERS ' CONVENTION. 135 



knowledge of the pest almost entirely consisted of its habits and life 

 history in other states and other climes— with the exception of a little 

 field work in Florida — which was more in the way of a scientific experi- 

 ment, from which^ apparently, no practical results were obtained. All 

 other artificial means of eradication were carefully considered; spray- 

 ing had proven a dismal failure; fumigation had recently been em- 

 ployed by the United States Government in an experimental way in 

 Florida, with the assistance of one of the County Horticultural Com- 

 missioners of Los Angeles County, and had proven quite satisfactory; 

 but this method of treatment' could not be considered in this case, for 

 the space of time before another brood of flies was due to appear was 

 quite short, and the size, location, and number of the trees were such 

 that to have attempted fumigation would have necessitated practically 

 the use of every fumigation tent in California. Other means were 

 considered, with the result that they were shown to be impractical under 

 the present conditions. The peculiar habit of this insect in attacking 

 only the leaves of its host plants gave hope of the success of a plan of 

 attack which it was finally decided to inaugurate. Most of the trees 

 affected were seedling varieties, and had no commercial value; again, 

 they were badly infested with several species of scale insects. These 

 facts were taken into consideration, and it was decided that the only 

 possible plan of campaign that gave any promise of success was to 

 promptly defoliate the trees. Time being the essential feature, to 

 prevent the immediate danger of spread; also, by defoliating we 

 would clean up the other pests mentioned, and leave the trees in shape 

 to bud to better varieties, making them commercially valuable as well 

 as ornamental. 



In addition to our regular preliminary work, practical men from the 

 county commissions, and men representing enormous horticultural hold- 

 ings from all over the State, who have had years of experience in 

 fighting all sorts of injurious insects with all known remedies, were 

 sent to the infested section — these sober, conservative horticulturists 

 Avere taken into conference before the final plan of campaign was 

 announced. 



Consequently on June 12, 1907, ' the defoliation order was issued, 

 the same being sent to all the county commissions in the State, as well 

 as in the infested county, as prescribed by law. 



It was also necessary to determine what plants besides the known 

 host plants might be infested, and inspectors were placed in the 

 field — careful, experienced men— with the result that additional host 

 plants were discovered that no writer on the subject had known to 

 be such. One especially was the lilac (Syringa. vulgaria), which 

 was found to harbor the pest in goodly numbers. As this shrub 

 was not mentioned in the defoliation order, considerable objection was 



