26 



twenty-third the fourth cast its first skin. All left the leaves after molting and settled on 

 young twigs. None of them had gone through the last molt when he left Los Angeles, 

 November sixth. He was afterwards informed by Mr. Alexander Craw, of Los Angeles, 

 that nearly all of the insects were full grown in February, and he therefore concluded that 

 the individuals observed by him would not attain full growth before that time. 



The mature male larva requires on an average about ten days from the time it begins to 

 form the cocoon before assuming the pupa state, and the piipa state lasts from two to 

 three weeks. The more reliable information we have been able to obtain would show that 

 at Los Angeles the average number of generations each year is three. 



HABITS. 



The fluted scale infests chiefly evergreen trees and seems to have an 

 especial liking for Australian plants, notably the acacia tribe, which on 

 account of this insect, in many sections of the State, has been replaced by 

 other trees. Of fruit trees, the orange family is especially subject to its 

 attacks, and its ravages in this country, as well as in South Africa, have 

 been very severe. But although there exist many plants which are but 

 little affected by this scale, there are scarcely any on which it may not 

 find lodgment for some time until a better suited subject is found. Fall- 

 ing to the ground they will exist on weeds and grass for some time, on 

 some, such as nettles, thriving most wonderfully. It is this habit that has 

 made this insect the most difficult to exterminate when well established. 



NATURAL ENEMIES OF ICERYA PURCHASI. 



It is a singular fact that after an existence of some twenty years in this 

 State, but few natural enemies have shown themselves. Under the head 

 of " Beneficial Insects," I have recorded the Scymnu^ marginicollis as eating 

 the eggs. In Professor Riley's report of 1886 I find the following underlines 

 on this point: 



Neither Mr. Coquillett nor Mr. Koebele (his agents in California) have 

 observed any birds feeding on the icerya. 



The only predaceous insects recorded by Mr. Coquillett to feed on it was 

 the larva of a species of chrysopa, or lace winged fly. The ambiguous 

 ladybug has been know^n to feed on the eggs when they were exposed to 

 view. 



Among predaceous insects recorded by Mr. Koebele, and sent to me. is the 

 larva of a small moth, which was found feeding on the dead larvae; if they 

 could live on the living scale I had no proof. 



Two beetles, Blnstinus and Perimego.toma, were found among dead larvae; 

 it is considered doubtful if they destroy living ones. 



The most efficient destroyer of the cottony cushion scale, at Los Angeles, is perhaps a 

 species of earwig, family Forficnlidve, neither "the geniis nor species of which we are able to 

 determine, from the fact that we have only seen immature specimens. According to Mr. 

 Koebele, this insect is often met with among the scales, and, from observations which he 

 made, feeds greedily upon the icerya in all the stages, tearing open the egg-masses and 

 eating the eggs, and also tearing and eating the mature insects, as well as the larva\ The 

 breeding habits of the mother earwig and her care of her iiock of young have been ob- 

 served by Mr. Koebele, but have been so well studied by European authors as to need no 

 detail here. 



Mr. Koebele also reports the occurrence in the scale masses, in large numbers, of a 

 minute whitish mite, which becomes of a reddish color when full fed, and which he thinks 

 destroys the female scales. We have not seen specimens of this naite, and are therefore 

 unable to determine it. 



Parasites.— It is a somewhat remarkable fact that no true parasites were ever bred from 

 the cottony cushion scale until the past summer, and still more remarkable that in the 

 course of their careful investigations, extending over a space of six months, neither Mr. 

 Coquillet nor Mr. Koebele succeeded in finding a single parasite tipon this insect. From 

 a number of scales, however, sent to Washington by Mr. Koebele November tenth, we 

 bred, on December eighth, two specimens of a small chalcid, which is, without question, a 



