THE MONTHLY BULLETIN. 107 



ENTOMOLOGICAL. 

 VEDALIA VS. ICERYA ON PEARS. 



By E. J. Branigan. 



During the past two years there have been frequent complaints from 

 the San Jose section of Santa Clara County of serious damage to pears 

 l)y the Cottony Cushion Scale. These complaints come to the State 

 Insectary mainly in the form of urgent reqiiests for Vedalia, the lady- 

 bird enemy of the scale. These ladybirds have been supplied where 

 possible, but both growers and horticultural experts soon came to the 

 conclusion that the Vedalia did not for some reason relish the cottony 

 cushion scale when breeding upon pears. No explanation has been 

 offered for this apparent discrimination by Vedalia. 



During the past season the pi-oblem of Icerya on pears became so 

 serious as to threaten the industry in certain restricted localities. The 



*^ 



Img. 20. — The hulvbird beetle. YtduHa 

 cnrdhifilis. (After Esslg, Mo. Bui., 

 Cal. Hort. Com.) 



black smut from the honeydew made it necessary to go to the great 

 expense of washing the fruit, and this is not only costly but reduces 

 the quality of the fruit. 



Recently the writer, being in the infested locality in Santa Clara 

 County for the purpose of obtaining cottony cushion scale for feeding 

 the Vedalia at the Insectary, took occasion to investigate the apparent 

 aversion of Vedalia to Icerya on pears. I believe the explanation is 

 simple enough. The constant spraying of the pears for the codling 

 moth with arsenate of lead seems to be the real reason for the failure 

 of Vedalia to gain a foothold in the pear orchards. The young scales, 

 and the egg masses as well, become thoroughly saturated with the 

 poison. This is of course fatal to both the adult and the young Vedalia. 

 and is sufficient to prevent their control of this pest on pears, while it is 

 thoroughly controlled in the same vicinity by Vedalia, when feeding 

 upon plants other than pear trees. To further test out this explanation 

 a quantity of pear twigs infested with scale and unsprayed was placed 

 in a cage at the Insectary, along with citrus twigs infested by the 



