COCCIDyE. 



231 



The arboreal genera are : Asterolecanium, Pseudococcm, Grypto- 

 coccus, and Apterococcus. With the exception of Asterolecanium, 

 these genera are, so far as our present knowledge goes, exclusively 

 arboreal. 



The remaining genera viz., Dadylopius, Ripersia, Antonina, 

 Ei'iococcus, and Gymnococcus are, as regards food-plants, very varied 

 indeed. Thus Dadylopius (" mealy-bug "), of which five species are 

 at present known, may feed on numerous greenhouse plants, grasses, 

 or sea-pinks ; Ripersia on a hothouse fern, on Stephanotis, roots of 

 grass, and even subterranean birds'- nests ; Antonina on bamboo; 

 Eriococcus on gorse, grasses, or heath ; and 

 Gymnococcus on stovehouse plants. 



Genus Asterolecanium. 



The females of this genus are completely 

 enclosed in a sac of opaque or semi-trans- 

 parent waxy or glass -like secretion. This 

 ovisac is usually termed a " test," and the 

 margins are generally furnished with a fringe 

 of waxen rods or plates. 



The adult females are apodous, and the 

 antenna? are either absent or rudimentary. 



Asterolecanium variolosum (Eatz.) 



This is a species which I found very 

 common in Cheshire, on the tips of the 

 young oak shoots. The female scale ad- 

 heres very closely to the young twig, so 

 much so, that she actually causes a de- 

 pression to be formed, and where they 

 are numerically strong, often kill the twig. 

 The appearance presented may be compared 

 (if the simile is not considered too grotesque) to the features of a 

 person who has suffered severely from small-pox (fig. 216). The 

 ovisac is made up of a " test " or scale, which is of a circular shape, 

 and around the lateral sides a curious fringe may be seen under the 

 microscope. The colour of the scale varies according to age : thus 



Fig. 216. Depressions on twigs 

 of oak caused by Astero- 

 lecanium variolosum (nat- 

 ural size). 



