HUNGERFORD: AQUATIC HEMIPTERA. Apel 
stripe by a spot of dark pigment. On the hind margin of the head there 
are two spots, visible only when the head is bent forward. The caudal 
margin of prothorax is margined with a dark band. Base of meso- 
thoracic wing-pads marked with dark irregular spot. Hind margin 
with arcuate band of color and two faint arcuate bands upon the disc. 
The metathorax is marked with pairs of irregular smoky spots as de- 
lineated. Abdomen markings as in former instars. 
Structural Peculiarities. The wing-pads are now well marked and ex- 
tend back slightly more than half the length of the margin of the meso- 
and metathorax taken together. Tibia as well as tarsus of hind leg with 
- swimming fringes. Claws of hind tarsus now not more than one-fifth 
the length of the tarsus. The claws present the peculiar incised ap- 
_ pearances as before. The middle femur is longer than the tarsus and 
tibia together. The marginal series of spines as delineated. 
Fourth Instar. 
Size. Length, 3.072 mm.; width of body, 1.43 mm.; width of head, 1.19 
mm.; distance between eyes, 0.39 mm. 
Shape. About as in third instar. 
Color. The ground color is pale fuscous with darker markings ranging 
from smoky to reddish-brown. The face bears the pair of smoky rec- 
tangular blotches noted in former instars. From above the vertex is 
marked by three longitudinal stripes. The median one is slender and the 
lateral ones irregular in outline. The thorax is marked as delineated in 
the plate. The darker part reddish-brown, the scroll on the metathorax 
being the most characteristic. The abdomen is crossed by reddish-brown 
transverse bands, which at the margin of abdomen blend into triangular 
smoky spots. The body of abdomen is further marked by two longitudinal 
broken bands of fairly dark pigment, one either side of the dorsal glands. 
These converge from the base of the abdomen to the caudal end, where 
_ they meet. The caudal margin of hind tarsus bears a roughly triangular 
dark blotch, its apex reaching in some cases two-thirds of the distance to 
the cephalic margin. 
Structural Peculiarities. The wing-pads now extend more than two- 
thirds the length of the meso- and metathorax. The hind limbs are now 
_ well adapted for swimming, the hind tarsus being broad and flat, and the 
_ Swimming fringe very complete. The claws are reduced now to perhaps 
- one-seventh of the length of the tarsus, and are less conspicuous than 
formerly. There is a small tibial comb of six short spines at distal end 
4 of the tibia. This structure is present but inconspicuous in the previous 
instar. The marginal series of spines as delineated. 
; Fifth Instar. 
Size. Length, 3.9 mm.; width of body, 1.7 mm.; width of head, 1.3 mm.; 
_ distance between eyes, 0.89 mm. 
_ Shape. As before, save that the length is greater in proportion to 
- width. 
4 Color. Color pattern substantially as in previous instar. The long 
_ wing-pads, however, are darker. 
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