222 



Usinger: Hemiptera 



Fig. 7:37. Mesovelia mulsanti White, macropterous male. Oahu, 

 T. H. (R. L. Usinger) (Zimmerman, 1948). 



but eggs embedded in plant tissue have been observed 

 to withstand winter temperatures, so it is possible 

 that this may be the normal method of overwintering. 

 Eggs are inserted in plant tissue at the water's edge 

 by means of the ovipositor. They are "elongate-oval 

 with a curved neck terminating in a flat surface which 

 marks the exposed end of the egg as it lies in situ in 

 the stem of some plant" (Hungerford, 1920). The 

 incubation period for M. mulsanti was recorded by 

 Hungerford as 7 to 9 days, for douglasensis (= amoena?) 

 12 days (Hoffmann). The average length of each of the 

 five nymphal instars for mulsanti was 3.4, 3.2, 3.5, 

 4.4, and 5.4. Comparable figures for douglasensis 

 were 4.3, 4.4, 5.4, and 7.1 days. Both species undergo 

 several generations in a season. 



Habitat. — Mesovelia mulsanti lives on the surface 

 of ponds and other bodies of standing water. Bog 

 lakes and ponds with much surface vegetation are 

 preferred. Typically, they forage on the floating 

 leaves of pond lillies, Typha, and the like, and run 

 out over the open water with remarkable agility, con- 

 sidering that their claws are inserted at the apices of 

 the tarsi. Hungerford (1917) found that they feed 

 readily on freshly killed insects on the surface of the 

 water, and he expressed the opinion that they also 

 spear small Crustacea that are associated with algae 

 and floating Typha. 



Mesovelia amoena is found in the same general area 



as mulsanti but in a quite different microhabitat. 

 These small bugs have been found in protected crev- 

 ices at the edges of ponds along the Colorado River 

 near Bard and also on moss-covered rocks in a small 

 hot-spring cave in Death Valley. In Colorado River 

 ponds they took to the open water only if forced to 

 do so, whereas mulsanti was running freely a few 

 inches away. 



Distribution. — Mesovelia mulsanti was described 

 from Brazil and M. amoena from the West Indies. As 

 pointed out by Jaczewski (1930), topotypical males of 

 both species must be studied before their taxonomie 

 status can be settled. Jaczewski proposed three sub- 

 species of mulsanti, basing them on the form of the 

 male genital claspers. His southern subspecies, 

 meridionalis, was recorded from as far south as 

 Argentina, caraiba was described from Central America 

 and the West Indies, and bisignata Uhler was con- 

 sidered to be the North American subspecies. The 

 differences described by Jaczewski were not partic- 

 ularly striking, and subsequent investigations have 

 not substantiated the classification into subspecies. 



In North America M. mulsanti is widely distributed, 



Fig. 7:38. Mesovelia mulsanti White, o, apterous 

 b, fifth (last) nymphal instar of macropterous form; 

 nymphal instar of apterous form (Hungerford, 1920). 



female; 

 :, fourth 



