PLATE | 
STYLETS OF A SAP-SUCKING 
INSECT, AN APHIS, IN POSITION 
IN THE PLANT TISSUE 
Note that the vascular bundle 
is being tapped. 

PHOTOMICROGRAPH OF A 
SECTION THROUGH THE 
OESOPHAGUS AND FOREGUIT 
OF AN APHIS, SHOWING 
THE VALVE (MARKED BY 
ARROW) WHICH PREVENTS 
REGURGITATION 
(Markham and Smith) 

