154 PROCEEDINGS OF TWENTY-SIXTH FRUIT-GROWERS' CONVENTION. 



and thus protecting itself against the attack of parasites. Good oil 

 washes have been successfully used as winter washes for its exter- 

 mination. 



Another scale which troubles the apple, and which is mostly found 

 on old trees, is the Oyster-shell scale {Mytilaspis pomorurrij Bouche). 

 It is not really considered a pest, and has very many enemies. Our 

 scale-eating ladybirds do their share in checking its spread, but several 

 chalcid flies, viz: Aphelinus mytilaspidis, Le Baron, and Aphelinus 

 fuscipenniSj Howd., and others keep the pest from spreading. I have 

 found this species on rosebushes and the passion-vine, and it is said to 

 infest a number of other plants. 



One of the most general feeders among scale insects is the Greedy 

 scale {Aspidiotus rapax, Comst.), which infests pear, apple, plum, 

 peach, cherry, and all kinds of ornamental shrubs. One of its favorite 

 foods is the Texas umbrella, but even the blue gum is not exempt from 

 its attack. The twice-stabbed ladybird {Chilocorus hivulnerus) and 

 Pilate ladybird (Exocomus pilatei) feed readily on it, but I believe its 

 best enemy is the chalcid fly (Aphelinus fuscipennis, Howd.). This is 

 probably a native species, as we find it on all our soft-wooded trees and 

 shrubs in very isolated places. 



There are numerous other scale insects which have been reported as 

 doing damage, but which as a general rule are not considered pests in 

 the orchard. Among the most common are: 



The Hemispherical scale (Lecanium hemisphsericum, Targ.), which is 

 found on chestnut, orange, oleander, and others. This scale has 

 numerous parasites; 



The English Walnut scale {Aspidiotus Juglans-regix, Comst.); 



The Rose scale (Aulocas^jis rosse, Sandb.); 



The Willow scale {Chionaspis ortholobis, Comst.); 



The Pine scale {Chionaspis pinifolise, Fitch); 



The Insignis Pine scale {PhysoJcermes insignicola, Craw); 



The Cottony Maple scale {Pulvinaria innumerahilis, Rath.); and a few 

 Mealy bugs. All of these are probably controlled by natural enemies, 

 as they have never been known to spread in great numbers. 



The Cottony-Cushion scale and the San Jose scale, as mentioned 

 above, demonstrate what we can expect from beneficial insects, provided 

 that we can find the right one in its native land. 



Before closing, I wish to call attention to the many close calls Cali- 

 fornia has had in introducing some of the worst scale insects known to 

 infest trees in foreign countries, and which were only prevented from 

 being established in our orchards by the establishment of a quarantine 

 department and its strict regulations, by a thorough system of orchard 

 and nursery inspection, and by the vigilance and conscientious work of 

 the Commissioners and the Quarantine Officer. 



