42 2 Ma rga rodince. 



CHAPTER XII. 

 Sub-family MARGARODIN^. 



This is a well-defined group characterised by a quiescent 

 encysted stage, in the female, interpolated between the active 

 larval and adult stages. The nymph (or nymphs — for there may 

 be more than one of these quiescent stages) is without any 

 rudiment of limbs, and the antennae — if present at all — are 

 reduced to the merest vestiges, comparable with the same organs 

 in the Diaspidina. Nothing remains but the mouth parts, and it 

 is doubtful if these are fully functional during the ultimate 

 nymphal stage. This is a remarkable divergence from the normal 

 procedure of development in the RhyncJiota, which belongs to the 

 section Ametabola, characterised by a gradual and uninterrupted 

 development from the larva to the adult insect. Mouth parts are 

 altogether wanting in the adult females of most of the genera, 

 vestigial in others, and fully developed in one genus only 

 {Stouiacoccus). 



Abdominal spiracles probably occur in all the genera, though 

 they have not yet been recorded for Callipappus. In this character, 

 and in the possession of compound eyes in the males of most 

 of the genera, the MargavodincB show their relationship with the 

 MonopJdehiiicB. The males of Steingelia and Stomacocais are 

 exceptional in being provided with simple ocelli only. The males 

 of those genera in which the eyes are more highly developed 

 {e.g. Mmgarodes, Callipappus, Xylococcus, Kuwania) are also 

 distinguished by the presence of a dorsal tuft of long silky 

 filaments springing from the penultimate segments of the abdomen, 

 in which characters they are associated with the Ortheziince ; 

 whereas such genera as Steingelia and Stoviacoccus, in which the 

 eyes are of a simpler type, lack the dorsal tuft, but may carry 

 a pair of simple white caudal filaments similar to those found in 

 the males of the Dactylopiince. Ccrlostoinidia appears to fill an 

 intermediate position, the males of this genus having faceted 

 eyes, but no dorso-abdominal tuft of filaments. 



Maigarodes, the type genus of the sub-family, contains species 

 adapted to a subterranean life. The anterior limbs in both sexes 



