1974] 
Smith — Life History of Abedus herberti 
281 
a smaller subspecies A. h. utahensis in northern Arizona and south- 
ern Utah. 
The first through the fourth instars all have two segmented an- 
tennae and one segmented pro-, and two segmented meso- and meta- 
tarsi. The beak is four segmented from the first instar to imago. 
One antennal segment is added in the fifth instar and usually another 
in the adult. All tarsi add one segment in the adult molt. 
The most noteworthy changes through instars are the allometric 
development of the wing pads (Fig. 3) and of the protarsal claws. 
Torre Bueno (1906) states that there is a progressive diminution in 
size (through the instars) of the anterior (external) protarsal claw 
of Belostoma flumineum and that the external claw finally disappears 
in the adult. This statement is erroneous on at least one count, but 
nevertheless focuses attention on an ontological aspect of phylogenetic 
significance. It is now known (Lauck and Menke 1961) that both 
Belostoma and Abedus have vestigial external protarsal claws. The 
other three genera in the Belostomatinae have two well developed 
protarsal claws as does the genus Lethocerus. In Abedus herberti and 
probably Belostoma as well, only the magnitude of the size difference 
between the external and internal protarsal claws increases with each 
molt due to nondevelopment of the external claw and continued 
growth of the internal. In the first instar relative length of the ex- 
ternal claw is 50 percent of the internal. This is reduced to about 
38 percent in the second, 30 percent in the third, 23 percent in the 
fourth, and 19 percent in the fifth instar. Curiously, in the adult 
the external is proportionally slightly longer than in the fifth instar 
and the internal claw is shorter and broader in the adult. This re- 
sults in an increase in the relative length of the external claw to 
about 28 percent that of the internal in the adult bug. 
Longevity 
A. herberti is a relatively large animal and is a sedentary hunter, 
both of which characteristics suggest that it might be long lived. This 
seems to be the case; several specimens have lived in the laboratory 
for up to one year and one in particular, a female collected on Octo- 
ber 14, 1972, lived until November 30, 1973 during which time she 
produced four sets of eggs totaling 344. Nymphs from the first 
through the third instars are probably subject to predation by other 
aquatic organisms. I have found first instar nymphs in the stomachs 
of trout taken at three forks of the Black River, Apache County, 
Arizona. Nymphal instars seem to play an important role in the 
