12 



A Brief Review of the Indigenous Coccidae of the British 



Islands. 



By E. Ernest Green, F.E.S., F.Z.S.— /iVrtJ April 2lth, 1922. 



It is not my intention to give a detailed account of our British 

 Coccidae. Such an account is already available in Newstead's 

 admirable Monograph, in two volumes, published by the Ray 

 Society. My present object is, rather, to attract the attention of 

 our field naturalists to this interesting but relatively neglected 

 family of insects. That the subject is by no means exhausted is 

 evidenced by the fact that, within the past eight years, I have been 

 able to add approximately thirty species to the British list, more 

 than half of which were new to science. 



Newstead's " Monograph of the British Coccidae " describes 90 

 distinct species, to which there have since been added another 37, 

 so that the list now stands at 127. Rather iiiore than half of these 

 (to be exact, 67) have been found only in glass-houses and must be 

 regarded as aliens introduced with foreign plants. In the present 

 paper I propose to ignore these aliens and to review (very briefly) 

 the superficial characters of such species as are to be found in the 

 open. 



But, first, I will attempt to explain to you how you may recog- 

 nize a Coccid when you have found it. This is not quite so simple 

 as, at first sight, it might appear to be. To the uninitiated, the 

 employment of a compound microscope will be necessary for the 

 purpose. 



It would be difficult to mention any single superficial character 

 that would be applicable to all the different subfamilies and genera 

 of Coccidae. Their external forms and appearance are so diverse 

 that they would never be supposed to bear any close relationship to 

 each other. What, for instance, could be more different than Af^pi- 

 diotiis hederae — a minute, limbless, yellow speck, covered by a 

 separate scale, and Ortliezia iirticae — an active species with con- 

 spicuous cushions and lamellae of compact white wax. But discus- 

 sion of the various modifications of form must be deferred until we 

 come to a consideration of the individual species. 



Coccidae may be distinguished from their nearest allies (the 

 Aphididae and Aleittodidae) by the following characters: — 



The females are invariably apterous. The body is not sharply 



