THE MONTHLY BIU>LETIN. 



205 



becomes wider tli;iii the head, the color in llic rilxlominal region is now 

 a deep yellow and tiie urates are prominent. From two to three days 

 at a temperatnre mean of f)2" F. eedysis or nionlting takes plaee and 

 the larva eiiti'rs the second stage, 'i'lie avei-agc length of lite of the first 

 stage l.irva was determined and varied fi-om forty-eight to seventy two 

 hours and averaged 57 hours. 



The Second Stage Larva. (Figure 63.) Characteristic of this 

 stage is the increase in size of the body, the head being practically of 

 the same dimensions as in the preceding stage. The body tapers gradu- 

 ally from the head to the tliird or fourth abdominal segment where the 

 width is greatest, the body gradually diminishing in size to the j^osterior 

 end. The urates are much more prominent in this stage than in the first. 



^C^12*iJiP* 



KiG. 63. — Calliephialtes .sp. 

 Second stage larva. Greatly 

 enlarged. (Original.) 



The head and the fifst three body segments are still of the whitish color 

 of the newly emerged larva, as well as the anal segment, l)ut the digestive 

 tract in the abdominal region gives that part a deeper yellow tint than 

 in the preceding stage. There is a slight curve to the body so con- 

 spicuous in the last stage. The mandibles are larger than in the first 

 stage but there is no perceptible change in shape. The oral ring is 

 heavier. The head, which in the first stage was about as wide as long, 

 is now transverse, the length ranging from .22 mm. to .3 mm., and the 

 width from .23 mm. to .4 mm., the average length being .25 mm. and 

 the width .32 mm. The larva varies in length from 1.5 mm. to 2.5 mm., 

 averaging 2.01 mm. and the variation in width is from .3 mm. to .6 mm., 

 averaging .49 mm. ; in other words, the length of the second stage larva 

 has increased in the proportions of 7 to 4 over the first stage larva, and 

 the width 5 to 3, while the head has not increased in length but has 

 increased in width 4 to 3. From forty-two to forty-eight hours at a 

 mean of 60° F. after the first moult skin is cast off, the segmental lines 

 of the body become indistinct, eedysis takes place again and the larva 

 enters the third stage. 



The Third Stage Larva. (Figure 64.) In the third stage the curve 

 of the body becomes more pronounced than in the preceding stage. The 

 color of the head and first two body segments is still whitish, as well as 

 the anal segment, but the digestive tract assumes a yellow-brown color. 

 The whitish urates are still conspicuous. The body is more widened 

 laterally and the larva is less active. As well as in the preceding stages, 

 the larva changes its point of feeding on the host frequently. The 

 lateral swollen areas are more distinct. The length of the larva varies in 

 this stage from 2.3 mm. to 3.6 mm., averaging 2.8 mm. and in width 

 .8 mm. to 1 mm., averaging .9 mm. The head averages .3 mm. in length 



