Back Swimmers

Notonectidae.

Back swimmers are so named because of their habit of swimming upside down. They are also recognized by their long, oarlike hind legs that pull in unison when the insect swims. The body is slender, boat shaped, and often colored with white, red, or greenish areas, although it is usually all dull brown. The fore tarsus is visibly two segmented, slender, and bare. Like their relatives, the giant water bugs, they have large eyes and a sharp beak with potent powers; their bite is very painful and often is the salvation of a specimen in the collector's clutches. Also like their relatives, they are predaceous, but the size of their prey is smaller, consisting of fly and beetle larvae, fish fry, and crustacea.

There are between 300 and 400 species, mostly in the dominant genera Notonecta, Martarega, and Buenoa. These are distributed almost everywhere where suitable sluggish water habitats are available but show considerable selectivity to specific niches determined by water conditions and prey availability (Gittleman 1975).

Notonecta are the largest (BL of most 12— 15 mm) and must rise frequently to take on oxygen from the atmosphere; males are silent. Buenoa are smaller (maximum BL 11 mm) and possess hemoglobin containing cells that store oxygen and assist them in remaining submerged for longer periods than other notonectids; males stridulate by means of a ridged protuberance on the inside of the fore tibia. B. pallens (fig. 8.5b) is a widespread species. Martarega are the smallest (maximum BL 10 mm) and are most commonly found at water's edge in slow-moving rivers and do not stridulate.

Since earliest times, Mexicans around Lake Texcoco and Chalco near Mexico City have collected Notonecta unifasciata (axaya-catl) and associated water boatmen, which they consume in various forms (Ancona 1933). The eggs (ahuautli, axayacatl, etc.) are cooked into a kind of bread (hautle); adults (ahuatle, bledo delagua) may be ground and mixed with saltpeter to make a salty hash (Bodenheimer 1951).

Refer to Bachmann (1977), Nieser (1981), and Polhemus (1982) for bibliographies on the regional fauna.

References

Ancona, L. 1933. El ahuatle de Texcoco. Inst.

Bachmann, A. O. 1977. Notonectidae. In S. H. Hurlbert, ed., Biota acuática de sudamérica austral. San Diego State University, San Diego. Pp. 193-195.

Bodenheimer, F. S. 1951. Insects as human food. Junk, The Hague.

Gittleman, S. H. 1975. The ecology of some Costa Rican backswimmers (Hemiptera: Notonectidae). Entomol. Soc. Amer. Ann. 68: 511-518.

Nieser, N. 1981. Notonectidae. In S. H. Hurlbert, G. Rodriguez, and N. Dias dos Santos, eds., Aquatic biota of tropical South America. Pt. 1. Arthropoda. San Diego State University, San Diego. Pp. 115-117.

Polhemus, J. T. 1982. Notonectidae. In S. H. Hurlbert and A. Villalobos Figueroa, eds.. Aquatic biota of Mexico, Central America and the West Indies. San Diego State University, San Diego. Pp. 306-308.

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