25-2 



Ap2)le and Pear Sucker 



There were many larvae bred from beginning to end. But I had 

 to replace those that died in the course of breeding. There are pecu- 

 liarities of each instar by means of which the different instars can 

 be distinguished. These peculiarities will be described below. 



Fig. 8. 



Fig. 9. 



III. Description of the Instars. 



{a) General description, (i) Colour. A larva of each stage 

 passes through the same cycle, though it is growing bigger in size. It 

 is bright yellow when it hatches out or has moulted. The colour 

 gradually changes to yellow-brown, or in some cases distinctly reddish. 

 This change in colour may be due to exposure to atmosphere. But 

 there is a complete change of colour in the nymphal stage, when it 

 becomes entirely green. The larva of the fourth instar changes its 

 colour from brown to pale green as it matures for the fourth moult. 



(ii) Secretion (Fig. 10). The larvae of these insects are unmistake- 

 ably recognised by their secretion. All the larvae, including the nymphs, 

 have opaque white secretion, a long thread of which is hanging out from 

 the hinder portion of the abdomen. This thread consists of a central core 

 of translucent liquid covered externally by the whitish material which 

 prevents its exuding and thus wetting the surface of a leaf. The larva 

 begins to secrete as soon as it hatches out or has moulted. The thread 

 in some cases reaches a great length ; at the end there is a big knob- 

 like swelling. If the thread is pricked, the translucent liquid exudes 

 and wets the surface. This secretion is of a waxy nature and is soluble 

 in alcohol. Besides this big thread issuing from the anus, there are 

 small spine-like threads projecting from the extremity of the abdomen. 

 They are shining and seem to change colour, which is not their intrinsic 



