THE SAN JOSE SCALE AND ITS CONTROL. 13 
following list of parasites which have been reared from the San Jose 
scale: Aphelinus fuscipenns How., Aphelinus mytilaspidis LeB., 
Aphelinus diaspidis How., Aspidiotiphagus citrinus How. (fig. 10), 
Anaphes gracilis How., Physcus varicornis How., Prospaltella aurantii 
How., Prospaltella pernciosi Tower, Prospaltella fasciativentris Gir., 
Ablerus clisiocampae Ashin., Rhopoideus citrinus How., Perissopterus 
pulchellus How., Arrhenophagus chionaspidis Auriv., Anagrus spiritus 
Gir., Signiphora ngrita Ashm., Coccophagus immaculatus How., Coc- 
cophagus lecanw Fitch, and Microterys sp. 
While the benefits arising from the work of these parasites are un- 
doubtedly great, the percentage of control of the scale thus accom- 
plished varies greatly with the locality and the time of year, and from 
season to season. The highest percentage of parasitism thus far 
observed, and far in excess of the average, is 90. The remaining 
—— Meee. 
Fic. 10.—Aspidiotiphagus citrinus, a hymenopterous parasite of the San Jose scale. Greatly enlarged. 
(From Howard.) 
10 per cent of healthy scales would suffice for reproduction of the 
scale in injurious numbers. It is, therefore, readily seen that, even 
with this high percentage of parasitism, the control of the scale by 
these agencies can not be depended upon. 
Considerable attention has been given to the subject of fungous 
diseases of the San Jose scale, and numerous attempts conducted in 
a thoroughly scientific manner, notably by Prof. P. H. Rolfs, director 
of the Florida Agricultural Experiment Station, have been made to 
utilize one of these parasitic plants in the control of the insect. The 
fungus in question, Sphaerostilbe coccophila, is cosmopolitan in its 
distribution, infesting many armored scale insects,! and in Florida 
and the territory adjacent to the Gulf it is quite generally present 
on scales in orchards and on shade and forest trees. Its abundance 
and effectiveness, however, depend upon certain weather conditions, 
and therefore vary considerably. 
1 Subfamily Diaspine. 
