DIPTERA. er + | 
It is fairly common at Ames, Iowa, but has not been observed as 
especially annoying to stock. It has a wide range, however, and 
deserves to be studied with reference to its early stages. 
Hart gives the following facts concerning the species, with descrip- 
tions of early stages: 
The present species was the most abundant tabanid larva in the vicinity of Havana 
last spring (1895) It first appeared in our collections September 14, when a num- 
ber were noted swimming amidst vegetation near the margin at Station B. In the 
spring they were found at nearly all of the stations, but more particularly in con- 
nection with tipulid, muscid, and Eristalis larvie, in matted accumulations of dead 
stems and leaves over mud. They were especially abundant March 30 in Flag Lake, 
where large plump larve appeared at every turn. It was a surprise to find a few of 
them upon the bottom in open, shallow water, far from shore, in the middle of 
Quiver Lake at Station A. Young larve have been common in connection with 
larve of Bittacomorpha and Limnophila at Station I since March 17. At Stations 
B and G they have been common in moist drifts of fine rabbish 
washed up by waves Pupz were found in the breeding cages 
May 10 and 23. One emerged May 27 and another tried to 
emerge June 2, but died and was removed from its case. 
The larvie resemble those of the lineola group in their stria- 
tion and coloration, but differ in their short laterad prothoracic 
areas and larger size. They are like atratus in size, but may be 
readily separated from it by their coarser lateral striation, 
straw-yellow tint, slender lateral vitte, and usually projecting 
terminal stigmatal spine. 
Larva: Length, 45-55 mm.; diameter, 6-7 mm.; bright straw 
yellow, varying in some young larve to nearly clear white, 
marked with light fuscous brown microscopic pubescence, 
usually paler at each stage than atratus. 
Lateral prothoracic striated areas not more than half as long 
as the dorsal, striation not finer than that of the middle and 
lower lateral areas of the mesothorax, striated portion shining; 
a small smooth spot adjoining the impressed line below; remain- 
ing upper thoracic areas a little less closely striated, but not 
strongly different from that of the prothorax; abdominal lateral 
areas a little more finely striate; dorsal and ventral areas with 
margin striated, disks nearly smooth in adult larve, last seg- 
ment more strongly striate, especially beneath. 
Dark annuli distinct, broad, including false feet, a distinct, 
transverse dorsal and ventral pale spot in front of the false feet; 
abdominal annuli often with a small triangular backward pro- 
longation on median line above. Prothoracic lateral space oceu- 
pied by a pale brownish fuscous quadrate spot in front of the 
striated space. Meso- and meta-thoracic lateral stripes usually distinct, but slender, 
scarcely dilated posteriorly, lateral edges of dorsal areas diverging; lateral stripes 
above the abdomen almost wanting, except on last two segments. In these stripes 
the punctures of the upper and lower rows are indicated by rounded pale dots, and 
those of the inner rows by elongate dots. Last segment with bases of respiratory 
tube and anal prominence encircled with dark rings, joined by a lateral connection, 
its dorsum with at most a short basal line or pair of dots on each side. Coarser 
pubescence of false feet tipped with pale brownish. 
Main internal trachex thick and noticeable, especially in young larve, lustrous, 
subparallel, not strongly sinuate, nearly straight posteriorly; terminal stigmatal 
spine dark reddish brown, smooth, usually protruded (fig. 32, p. 68), 
Fig. 31.— Tabanus 
stygtus: larva (after 
Hart). 
