298 



J. W. SCOTT MACFIE. 



Head (fig. 1). The large size of the head is a very noticeable feature of the larvae 

 of the first phase, but later it is subordinated by the great development of the thorax. 

 In the first phase the head was variable in shape ; in some larvae it was rather 

 broader than long, and measured about 16 by 17 units ; in others it was longer than 

 broad and measured about 14 by 10 or 11 units. In the second phase the head was 

 as broad as it w^as long or broader, and in the third and fourth phases it was decidedly 

 broader than long. The " egg-burster," situated dorsally about the middle of the 

 head, is a conspicuous feature in the first phase (fig. 1,1). 



Fig. 1. Head of the larva of Stegomyia fasciata in the four stages. 



Antenna (fig. 1). The antennae are relatively short and simple structures 

 throughout the larval period. In the first phase they measured almost invariably 

 7 units, but in a few larvae they appeared to be half or one unit shorter ; in the 

 second phase they measured 8 to 10 units, but were most commonly 9 ; in the third 

 phase 13 to 14 units, and in the fourth and last phase 18 to 20. They were straight 

 in most larvae, but sometimes they curved slightly. The latter form was most 

 frequently seen in the larvae of the first phase, especially in those that had long- 

 shaped heads. 



The second joint of the antenna is very poorly developed in the young larvae, but 

 is somewhat larger and partly chitinised in the older individuals. Of the hairs at the 

 tip of the antenna there is one which exceeds all the others in length, averaging 3 units 

 in the first phase, about the same in the second, 3 to 4 in the third, and 4 to 5 in the 

 fourth phase. The hair therefore increases slightly in length as the larva matures, 

 but its growth is not proportional to the growth of the antenna. 



