VIII 



COCCIDAE- SCALE-INSECTS 



593 



galls. This highly aberrant group is, however, peculiar to 

 Australia; elsewhere very few gall -making Coccids have been 

 discovered. 



There are upwards of 800 species of Coccidae at present 

 known. 1 The family was monographed by Signoret about twenty- 

 five years ago, and since then there has been 

 very much matter concerning them published 

 in a scattered manner. 2 No general work 

 has been published on the British species, 

 but Mr. Newstead is preparing one. The 

 classification of Insects so minute as Coc- 

 cidae, and with such extreme difference in 

 the sexes, is, of course, a matter of great 

 difficulty ; the best divisions are those given 

 by Green in his Coccidae of Ceylon? 



The fact that there is only one pair of 

 wings in the perfect male Coccicl would appear 

 to ally these Insects with the Diptera ; these 

 Coccidae have, too, like the Diptera, a small 

 appendage on each side of the metathorax. 

 Witlaczil shows that these little processes may 

 really represent a pair of wings, inasmuch as 

 they are developed from imperfect folds of 

 hypodermis, i.e. imaginal discs. Beyond these 

 facts and the occurrence in certain females 

 (Margarodes) of a great histolysis during the 

 post-embryonic development, there is nothing to indicate any rela- 

 tionship between Coccidae and Diptera. It has been shown by 

 Biley that these little processes, in some forms, serve as hooks to 

 attach or control the true wings, and this function is never assumed 

 by the halteres of Diptera. Although Coccidae are placed next 

 Aphidae, yet the two families appear to be really very different. 

 The modes of reproduction so peculiar in Aphidae reappear to a 

 certain extent in Coccidae, but are associated with profound 



1 A catalogue of Coccidae has recently been published by Mr. T. D. A. Cock.'nT; 

 in Bull. Illinois Lab. iv. 1896, pp. 318-339. 



FIG. 289. Dactyl <>}>! i'. f 

 lirm/ispinus. Female 

 on portion of a fig- 

 leaf. (After Berlese.) 



2 Signoret's papers are to be found in eighteen parts in Ann. Nor. fnt. 

 1868 to 1876: the most considerable subsequent systematic JIM per- ;u-c thus. 

 Maskell in the Transactions of the New Zealand Institute- from Is7s t llif present 

 time. 



3 Coccidae of Ceylon, pt. 1, 1896, p. 16. 



VOL. VI 2 Q 



