220 THE UNIVERSITY SCIENCE BULLETIN. 
setz, about equal to tibia in length. Second legs; tarsus equal to tibia, 
both together about as long as femur. Third legs with femora, but 
slightly flattened, tarsus nearly as long as femur and tibia together, 
clothed with setz, these longest at the joint, becoming much shorter 
distally. Colour very transparent. A median grayish line on thorax.” 
Third Instar. 
“Length, 2 mm. Width, 1 mm. Head as before. Eyes a little more 
than one-fifth the head-width in width. The wing-pads first appear; 
about three-fifths the length of thorax, sparsely hairy. Thorax one- 
half as long as wide. Abdomen as before, fringed on the sides by rather 
long setz, the posterior angles with conspicuous tufts. Ventral surface 
sparsely pilose. 
“Tarsi all 1-jointed. The whole first leg about equal in length to the 
femur of second leg. Tarsus about three times as long as broad, termi- 
nated by a sharp spine. Second legs slender; tarsal claws as long as 
tarsus, other joints as in third leg, all feebly setose. Third legs; tarsus 
1% times the tibia, the latter equal to femur. Tibia and femur together 
about equal to femur of second leg. Abdomen strongly truncate.” 
Fourth Instar. 
“Length, 8mm. Width, 1.2 mm. Very much more pigmented and 
less transparent than previous instars. Posterior margin of head, pos- 
terior angles of eyes, and posterior margin of thorax fuscous. Anterior 
margin of thorax and inner edge of wing-pads with rather dense 
brownish-black hairs. These together with the pigmented posterior mar- 
gin of the thorax form a square; a median patch of brown hair joining 
the band on the anterior margin. General surface of thorax smoky 
brown with narrow median clear line, and a paler transverse band in 
the middle. Head pale brown with darker shading on vertex. Whole 
dorsal surface of thorax and abdomen sparsely hairy, the abdominal 
segments faintly indicated by transverse brown stripes. A median longi- 
tudinal white stripe one-third the body-width in diameter runs the length 
of the dorsal surface of the abdomen. Within this is a series of large 
pale brown blotches, one on each segment, the third and fourth of these 
with a distinct crescent of chestnut brown, marginal third of abdomen 
smoky, fringed with cilia, but these less conspicuous because of the 
general hairiness of the body. The wing-pads hardly extend beyond the 
thorax. 
“Tarsi all 1-jointed. First legs as before. Second leg with femur 
as long as width of head, equal to tibia and tarsus together. Claws 
one-fifth longer than tarsus. Third leg with tarsus equal to width of. 
head, feathered with dense hairs. Antenne one-half of the length of 
tarsus of first leg. Interorbital space two-thirds the width of head, and 
equal to three-fourths the length from vertex to tip of beak.” 
Fifth Instar. 
“Length, 3.8 mm. Width, 1.4 mm. Dorsal marking as in previous 
instar, but more intensified. The two median dark brown marks of third 
and fourth abdominal terga oblong, surrounded by a larger oblong one 
of smoky brown. Hairy covering of wing-pads and thorax conspicuous, 
the median patch of the anterior border extending more than one-third 
the length of thorax down the median axis. Wing-pads extend half way 
to third abdominal segment. Beak brownish, with short pubescence. 
Legs pure white, antenne no larger than before, but fringed with short 
cilia. Tarsi of first two legs one-jointed; those of third leg two-jointed, 
otherwise legs as before. 
“In comparing the various larval stages one is struck by marked in- 
crease in the size of the eyes relative to the size of the head as de- 
velopment proceeds. Another point is of great theoretical interest. As is 
