466 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



MISCELLANEOUS INSECTS. 



THE COTTONY CUSHION-SCALE. 

 (Jcer?/a pwrc/iasz Maskell.) 



Order Hemiptera; family CocciDiE. 



[Plates I, II, III, IV, and V.] 



INTRODUCTORY. 



"We have, during the year, been condncting a special investigation 

 of the habits of and remedies for the so-called Cottony Cushion-scale 

 of California, an insect which for the last eight years has occupied 

 much of the attention of the horticulturists of that State. We have 

 been much interested in this pest since it was originally sent to us 

 while in Missouri by Mr. R, H. Stretch from San Francisco in 1872, 

 and have watched its increase and spread, until it became evident from 

 its alarming prolificacy, from the great diversity of its food-plants, 

 from its supposed immunity from the attacks of natural enemies, and 

 from the protection against the action of insecticides afforded by its 

 abundant waxy excretions, that especial study and exj)eriment were 

 much needed. 



The following account of the insect is prepared from published 

 accounts and unpublished correspondence; from our biologic notes 

 made at the office in Washington, chiefly in 1878, 1880, and 1886; but 

 more especially from our recent experience in the field (which the 

 delay in publishing the report has enabled us to partly embody), and 

 the observations of Messrs. Coquillett and Koebele, whose reports on 

 experiments made to destroy it will be found given in full among 

 the reports of agents. 



GEOGRAPHICAL DISTRIBUTION. 



So far as we have been able to learn, up to the date of present 

 writing, the Cottony Cushion-scale is found only in California, in 

 Australia, in South Africa, and in New Zealand. We shall discuss 

 its introduction into California and its jDresent limitations in that 

 State in subsequent sections of this paper, and what we know of its 

 spread in the other countries mentioned is here considered. 



In Australia. — As will appear farther on, the evidence collected 

 goes to prove that this insect is indigenous to Australia and has been 

 exported from this colony to the two other colonies in which it occurs 

 and to the United States. We have very few facts as to its occur- 

 rence in Australia and these are taken at second hand. Wo have 

 addressed communications to a number of naturalists in different por- 

 tions of that country, but their replies have at this Avriting not been 

 received. From the '' Rejoort of the Commission api:)ointed by his 

 excellency the governor to inquire into and report upon the means 

 of exterminating the insect of the family 'CoccidcE,' commonly known 

 as the 'Australian Bug,'" publisherl at Cape Town, 1877, and from the 

 letter of Mr. Roland Trimen, dated February 5, 1877, and xuiblished 

 by the government secretary of Cape Colony as "Government Notice 

 No. 118, 1877," we find that at that time sj^ecimens of the insect were 

 sent from Caj)e Town to different portions of Australia, and that re- 



