ECONOMIC ZOOLOGY ENTOMOLOGY. 555 



1880 at which time it was found to be well established in various parts of Cali- 

 fornia. In America it has also been recorded from Brazil, the West Indies, 

 Mexico, Massachusetts, South Carolina, Ohio, and Florida. In California it 

 occurs to a greater or less extent in practically all of the counties, but is limited 

 as a pest to the citrus belt of southern California, the different deoiduous trees 

 in the coast counties about San Francisco Bay, and to some extent on olive 

 trees of the interior valleys. " In the citrus area of southern California, the 

 black scale is the most widely distributed of all the scale pests. It occurs in all 

 of the counties from Santa Barbara to San Diego. It is less abundant in the 

 interior counties of Riverside and San Bernardino; but even here in some sec- 

 tions it becomes an important pest. But the black scale becomes most abundant 

 nearer the coast, since it is a scale that is more adapted to the cooler and 

 moister climate of such sections." 



The important injury to citrus fruits is due to the sooty mold fungus (Meliola 

 camellia'), which develops in the honeydew which the scale excretes. In Cali- 

 fornia the scale ranks first as a pest on citrus trees. "On the olive, pepper, and 

 oleander, it also occurs in abundance, and often does much injury, but it is only 

 rarely that control work is imdertaken on these trees. Of the deciduous trees 

 the apricot and prune are the worst attacked. On these trees Lecanium corni 

 is often associated with the black, and is the more important pest of the two in 

 the deciduous fruit sections. But the black scale often does reach the status 

 of a pest on these trees and spraying is done to control it It is not uncommon 

 to see apricot trees completely covered with sooty mold fungus as a result of 

 black scale infestation." 



Technical descriptions are given of the stages in connection with a detailed 

 report of studies of the life history and habits of this scale, which are taken up 

 under the following headings: The egg; the active larva, including experiments 

 on the rate of travel over sand and orchard soil, a report of which has been pre- 

 viously noted (E. S. R., 26, p. 149) ; the fixed young; the adult female; the de- 

 velopment of the male; and seasonal history. 



" There is usually but one complete generation of the black scale in a season. 

 The great majority of these come to maturity in the spring months, so that 

 most of the eggs are deposited by midsummer. The time of maturing of the 

 bulk of the black scales will vary somewhat from year to year, and in some 

 years there will be a much more uniform hatch than others. Taking a specific 

 season, as 1910 in the Los Angeles district, the height of egg-laying was during 

 the third week in May. The greatest production of young was about the third 

 week in June. Eggs will be deposited by a single scale during a period of 2 

 months. By the middle of July, therefore, most of the young had already ap- 

 peared." In summarizing the length of the life cycle of the male during the 

 summer months, it was found to be as follows: First stage Is months; second 

 stage, 1 month; propupa, 8 days; pupa, 10 days; adult, 3 days; total 96 days, 

 or about 3 months. 



A somewhat detailed account is given of the life history, habits, etc., of 

 ScuteUista cyanea, the most important insect enemy of the black scale in Cali- 

 fornia. This parasite was first successfully introduced into this country from 

 Italy in 1900 and has since become well established in California in most of the 

 sections where the scale occurs in injurious numbers. The percentage of scales 

 parasitized often runs as high as 75 per cent, but this varies greatly in different 

 sections and in the same section in different years. A brief account is also 

 given of the hyperparasite Cerchyskis sp., which is occasionally found under the 

 old black scales ii stead of the ScuteUista pupa at the expense of which it de- 

 velops, of Tomocera calif ornica,which parasitizes the eggs of the black scale, and of 

 35693°— Xo. 6—12 5 



