FUMIGATION OF APPLES FOR THE SAN JOSE SCALE. 



INTRODUCTION. 



The possibility of the establishment in new localities of the San 

 Jose scale (Aspidiotus perniciosus Comst.) from shipments of scale- 

 infested fruit, principally apples and pears, has been the subject of 

 frequent discussion among entomologists and others. On the whole 

 it seems to be the consensus of opinion that, although this danger un- 

 doubtedly exists, the chances of establishment from this source are 

 exceedingly remote. 



The great bulk of the fruit harboring this insect is sold in cities and 

 towns and the parings and refuse are mostly disposed of in a way to 

 effectively prevent any young crawling "lice" from reaching plants 

 upon which they could establish themselves. The fruit, furthermore, 

 is offered for sale mostly during the late fall and winter, a time when 

 the temperature is too low to favor the activity of the crawling young 

 or to favor their production by the adult females. The danger of 

 their establishment would perhaps be greatest in the case of varieties 

 of fruit maturing in late summer or early fall, which would reach the 

 markets some weeks before the approach of cool weather, thus afford- 

 ing a period for the breeding of the scales present and, should they 

 succeed in reaching a suitable host plant, for the necessary growth 

 of the young to enable them to survive the winter. Their chances 

 of survival would be correspondingly increased if the infested fruit 

 were shipped to a warm or subtropical climate. Also, infested fruit 

 kept for a time during the winter in a warm room, or in a conservatory, 

 closely adjacent to suitable potted or other host plants, might result 

 in the infestation of these plants and the later spreading of the insects 

 to plants out of doors. 



In the case of fruit used for culinary and dessert purposes, the 

 refuse parts, as peel and core, are very largely consigned to the gar- 

 bage, effectively eliminating any danger from that source. With fruit 

 eaten out of doors, as obtained from fruit stands, it is conceivable 

 that the refuse parts might by a strange chance be discarded in a way 

 to constitute a source of danger. Thus, a pedestrian passing along 

 a street or country road, in the act of eating an apple, might care- 

 lessly throw aside the peel, which lodging in a suitable host plant 

 might result in the scales obtaining a foothold. But it must be 

 89165— Bull. 84r-09 2 7 



