14 Characters and Classification. 



CHAPTER III. 



Characters and Classification. 



The Coccidas — commonly known by the name of Scale Insects 

 or Scale-bugs — are a subdivision of the order Hcmiptera. This 

 order comprises two sub-orders, the Homoptera and Hetcroptera, 

 both of which are characterised by the presence of suctorial mouths 

 and an incomplete metamorphosis. 



The Coccidae are considered to belong to the first of these 

 divisions — the Homoptera. There is, however, one point in which 

 they do not conform with that group. The wings of typical 

 Homoptera are not carried horizontally, but slope upwards and 

 inwards, their inner margins meeting above the middle of the back 

 without overlapping. We can only judge of this character in the 

 Coccidae by the winged males, and in these the wings are carried 

 horizontally above the back of the insect when at rest, often com- 

 pletely overlapping each other — a character according rather with 

 the Heteroptera. 



The Coccidse may be distinguished from their nearest allies by 

 the following characters : — 



1. The absence of wings in the females (//. \. fig. lo). 



2. The presence in the adult males of only two wings, supple- 



mented by a pair of hooked organs representing the missing 

 hind wings (//. W. fig. 2); which organs are homologous 

 with the * halteres ' of Diptera, but, unlike the latter, are 

 connected with the wings and serve to strengthen them 

 during flight. 



3. The legs in both sexes (when present) terminating in a single 



claw and having normally only one joint in the tarsus 

 (//. II. fig. 6). (An exception occurs in the abnormal 

 genus Exm'etopiis, Newst., in which the anterior tarsi are 

 two-jointed ; and Professor Cockerell has quite recently 

 described a gall-making Coccid from America, Oliffiella 

 cristicola, in which the same peculiarity exists.) 



