202 



MK. A. M. ALTSON ON THE LIFE-HISTORY AND 



distorted appearance — indicating the severance of a muscle — or is 

 shrivelled and excessively wrinkled (text-fig. 8). 



The first instar larva, with the exception of its brownish head, 

 is translucent white and glabrous throughout ; the integument is 

 very soft and easily damaged. 



Text-fig. 3 illustrates a larva of the second instar, in which the 

 capsule head has disappeared and has given place to one the type 

 of which remains constant in the later instars. The particular 



Text-fisfure 3. 



Second instai- larva of A. manducator. Greatly magnified. Original. 



larva illustrated was removed from a Calliphora sp. puparium, 

 and was placed in a watch-glass containing three macerated fly- 

 nymphs with a few drops of water added to reduce the density, 

 and with the aid of a microscope it was kept under observation 

 for more than half-an-hour whilst feeding. The larva remained 

 quite motionless during this time, its mouth-parts alone were 

 constantly working; no movement of the mandibles was observed, 

 but the extensive lip-like labium was seen to be continually 

 moving with a "rippling" action whilst the liquid was being 

 absorbed. The abdominal vesicle has proportionately shortened. 

 The mid-intestine now shows up clearly, swollen with food and 

 giving a pale yellow colour to the larva. 



The intermediate instars show no superficial difference from 

 the second, beyond the shortening of the " tail ''-like abdominal 

 vesicle and the increase in the size of the larva and corresponding 

 swelling of the mid-intestine. 



Text-figure 4. 



Full- 



jrown larva of A. manducator 

 Length 4'25 mm. Or 



Greatlj' magnified. 

 nnal. 



The last instar larva (text-tig 4) differs from the preceding 

 instars in that —with the exception of the cephalic and posterior 



