554 EXPERIMENT STATION RECORD. 



The red scale, originally described from New Zealand iu 1878, was first 

 observed in this country in 1880, in which year it was found infesting orange 

 trees at San Gabriel and Los Angeles. While recorded from many other food 

 plants than citrus trees, in California it is limited as a pest entirely to the 

 citrus, so that its distribution is governed largely by this host plant. 



The red scale is deemed the second most important insect enemy of citrus 

 trees in California and the total amount of control work directed against it 

 and the yellow scale, which is a variety of the red, nearly, if not quite, equals 

 that against the black scale. " No citrus scale in California so quickly and so 

 permanently injures the tree as the red scale. . . . Practically the entire tree 

 may be killed . . . sometimes in one or two years' infestation. It infests all 

 parts of the tree, leaves, branches, fruit. It not only causes a dropping of the 

 leaves, but actually kills large branches. Aside from this permanent and 

 serious injury to the tree, the presence of the scale on the fruit renders it 

 unmarketable. Trees that do not have a severe infestation of the scale, and 

 where the tree itself is not seriously injured, may have fruit badly infested by 

 the scale." 



As regards the life history, " The average length of the life cycle from the 

 active young to the appearance of young again is about 3 months. During the 

 warmer weather it will run slightly under this, and during the coldest weather 

 it will run considerably more, the extremes being from 72 days to nearly 150 

 days. Four generations a year will be the largest number in a season. It is 

 not unlikely that this number occurs in the warmer sections — as Redlands and 

 Riverside. But in most sections 3 generations, with a partial fourth, will 

 represent the actual conditions. Starting with April 1, the beginning of the 

 next generation will be about July 1. Those young api>earing at this time will 

 be producing young themselves by the first of October. This will make 2 

 generations during the months of greatest activity. Those young appearing in 

 October may not, as our life history work has shown, give rise to young again 

 before February or March. This makes 3 full generations, with a partial fourth, 

 for conditions as they obtain at Whittier." 



An account by the author rela^ng to the locomotion and spread of this and 

 other scale insects has been previously noted (E. S. R., 26, p. 149). 



Aphelinvs diaspidis is its most common parasite at the present time. Ex- 

 aminations and counts made at various times during the past 3 years have 

 failed to show that its parasitism exceeds 10 per cent. Descriptions of its 

 stages and a brief account of its life history and habits are presented. Other 

 parasites noted are Prospaltella aurantii, Coccophagus Innulatus, Signiphora 

 occidental is, Aphycus immaculatus, and Alaptus criococci. RhizoMus lopanthw 

 and the steel-blue ladybird beetle (Orchiis chalyheus) are mentioned as preda- 

 tory enemies. 



The yellow variety of this scale (C. aurantii citrinus) is widely distributed 

 over the citrus belt of southern California and often associated more or less 

 with aurantii. In addition to its occurrence in the southern part of the State, 

 it is also found on the citrus trees of the Sacramento Valley. Aspidiotiphagns 

 citrinus, formerly known in California as the golden chalcid, which has beeu 

 met with largely in connection with the yellow scale, is said to be most abundant 

 in Santa Barbara County. 



A bibliography of the literature issued since the publication of Mrs. Fernald's 

 catalogue of the Coccidte in 1903 (E. S. R., 15, p. 278), furnished by E, R. 

 Sasscer of the Bureau of Entomology of this Department, is appended. 



The black scale (Saissetia oleae), H. J. Quayle and E. W. Rust (California 

 8ta. Bui. 223, pp. 151-200, pis. 8, figs. 2.'f). — This scale, which was described in 

 1782 from specimens taken on the olive, was first recorded from this country in 



