750 
RHYNCHOTA. 
structure, like a tongue (the lingula) from which honey-dew is secreted ; 
this orifice is covered by a hinged plate (the operculum). In this state, 
the nymph has its rostral setae buried in the tissues of the host plant, 
and feeds on the sap it extracts. In addition to producing honey-dew, 
it produces the wax it is covered in ; it is apparently uncertain whether 
honey-dew is or is not distinct from the excreta; it is stated to be so 
in Psyllidce, but not in Aphidce; we believe it is not distinct in Coccidce 
or Aleurodidce in all cases. 
Fig. 526— Aleurodes eugenic vae aurantii. A. Pupae on leaf. 
B. Pupa case. C. Diagram of pupa case. D. One radiating 
patch of 0. E. Margin of pupa case. F. Vasiform Orifice, 
operculum and lingula (diagrammatic). (I, M. N.) 
In the nymph state there are two moults, followed by a moult lead¬ 
ing to the pupa stage, i.e., there are in all the following instars :— 
1st instar, active, followed by 1st moult. 
2nd ,, scale-like, followed by 2nd moult. 
3rd ,, scale-like, followed by 3rd moult. 
Pupa ,, in the scale, followed by 4th moult. 
Winged imago. 
