OF THE FAMILY COCCIDAE 29 



The epistemum (eps 3 ) is small and subtriangular in shape, but when the haltere is 

 present it expands in a ventral direction ; in some species (e.g. E. tiliae and R. 

 spiraeae ; Text-figs. 3, 9) its anterior margin is partly bounded by a more or less 

 developed ridge, resembling the subepisternal ridge of the mesothorax. The 

 epimeron (epm 3 ) is represented by an irregular, posteriorly produced sclerite. In 

 most species a vestigial precoxal ridge (pcr 3 ) extends anteriorly for a short distance 

 along the ventral margin of the epistemum, but the absence or presence of this ridge 

 varies individually. The metathoracic spiracle (sp 3 ), supported by a peritreme (ptr 3 ), 

 is situated in the membrane anterior to the epistemum. 



The metasternum (stn 3 ) is usually represented by a fairly large, irregular, median 

 plate, which is generally more heavily sclerotized anteriorly and weaker posteriorly, 

 but in some species (e.g. S. prunastri, Text-fig. 22 ; Ceroplastes spp., Text-figs. 41, 

 43) its posterior part is entirely membranous and only a narrow strip of it remains 

 anteriorly. In Eriopeltis sp. (Text-fig. 13) small and irregular sclerotized areas are 

 situated anterior to this plate. The sternal apophyses are absent and this makes 

 it difficult to establish the homologies of the metasternal structures. The rather 

 similar topographical conditions in the Pseudococcidae, in which the metasternal 

 apophyses are present (Giliomee, 1961), indicate that the large metasternal plate of 

 the Coccidae represents a sternellum and that the small sclerites found in Eriopeltis 

 sp. corresponds to a basisternum. This conclusion is supported by the position of 

 the sternal apophyses and the large sternellum in Margarodes (Theron, 1958), and 

 the general structure of the meso- and metasterna in Aphis (Weber, 1928). Ghauri's 

 (1962) interpretation of corresponding sclerites in the Diaspididae as a metabasi- 

 sternum and mesosternellum respectively, consequently appears to be incorrect. 



Habib (1956) recognized the inverted nature of the metanotum ; Ezzat (1956) and 

 Borchsenius (1957) illustrated the pleural sclerotization but do not discuss it in any 

 detail ; Theron (1958) overlooked the postnotal and sternal sclerites in P. pomer- 

 anicum. 



Dermal structures. The fleshy and hair-like setae are arranged in the following 

 groups : 



(i) Metatergal setae (mts), occurring laterodorsally, anterior to the postnotal 

 sclerite. They usually consist of a single hair-like seta on each side, but in the 

 INGLISIA and COCCUS groups (Text-figs. 29-43) U P to 10 fleshy setae may also 

 be present in this region. In Ceroplastes spp. only fleshy setae are present and in 

 E. tiliae, P. piceae, E. pela and Genus A no metatergal setae were observed. The 

 setae of this region are sometimes difficult to observe because of the heavy sclerotiza- 

 tion of the invaginated structures which lie directly underneath. 



(ii) Dorsospiracidar setae (dss), which are situated pleurally, dorsal to the meta- 

 spiracle and in line with the pleural setae of the abdomen. When they are numerous 

 they are sometimes difficult to separate from the metatergal setae. They are only 

 present in the INGLISIA and COCCUS groups. The number of fleshy setae varies 

 from 1-8 (average 3-6) in /. theobromae to 10-23 (average 15) in P. acericola ; hair- 

 like setae are rarely present and never total more than 3. 



