382 Illinois State Laboratory of Natural History. 



honey locust and mountain ash. Common in Illinois; 

 collected by the author. 



Types in collections of the Illinois State Laboratory' 

 of Natural History and of the United States National 

 Museum, and in the author's collection. 



I first discovered this species on English morello 

 cherry-trees in Champaign, Illinois, December, 1894. 

 It is very generally distributed over Illinois, and 

 from what I have seen of its attack I consider it the 

 most dangerous scale insect of the orchard now estab- 

 lished in the State. Cherry seems to be its favorite food 

 plant, and I have found it on wild cherry at Champaign, 

 Decatur, Edgewood, and Eldorado. I therefore propose 

 for it the popular name, "cherry scale." Its specific 

 name is in honor of Professor S. A. Forbes, State 

 Entomologist of Illinois. It attacks the trunk and 

 branches of the cherry and is found occasionally upon 

 the leaves and fruit. In June, 1896, I found a few par- 

 tially matured scales of this species on cherries; July 6, 

 1895, I collected several currants on which they were 

 found; and August 14, 1895, I gathered several apples 

 which contained scales of fully developed females of the 

 cherry- scale. 



I have bred the following seven species of hymenop- 

 terous parasites* from this scale insect : Prospalta murt- 

 feldti (How.), Prospalta aurantii (How.), Perissopterus 

 pulchellus (How.), Signiphora nigrita (Howard MS.), 

 Arrhenophagxis chionaspidis (Aur.), Ablerus clisiocampos, 

 (Ashm.), and an undetermined species belonging to the 

 Encyrtinae. Aside from these parasites, I have very often 

 seen small whitish mites under the scales, especially 

 under male scales containing pupae, and in many cases 

 the pupae were dead. The twice-stabbed ladybug, Chiloc- 

 orus hividnerus, and its larva, also feed voraciously 

 on this scale. 



*A11 the hvnienopteroiis parasites mentioned in this paper have been examined and 

 determined by Mr. L. O. Howard, United States Entomologist, of Washington, D. C. 

 I am also under oblijiatinns to Mr.Howard, to his Assistant Mr. Theo. Perprande, and to 

 Prof. T. D. A. Cockerel], lor various favors rendered in the examination of coccid 

 material. » 



