A field life history study of Mesovelia mulsanti was conducted in south­ern Illinois, the results of which are compared with those from an earlier study also conducted in southern Illinois. The two studies differed in the collecting techniques used (quadrat sampler versus aquatic net). Results of the present study give a clearer picture of the life history of this insect be­ cause the quadrat sampler collected representative samples of nymphs and adults more effectively than the aquatic net and, thus, the quadrat samples more accurately represented the actual chronology of the annual generations

McPherson, J. E

Taylor, Steven J

English

Valparaiso University

The Great Lakes Entomologist Volume 33 Numbers 3 & 4 - Fall/Winter 2000 Numbers 3 & 4 - Fall/Winter 2000 Article 8 October 2000 Comparison of Two Population Sampling Methods Used in Field Life History Studies of Mesovelia Mulsanti (Heteroptera: Gerromorpha: Mesoveliidae) in Southern Illinois Steven J. Taylor Illinois Natural History Survey J. E. McPherson Southern Illinois University Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Taylor, Steven J. and McPherson, J. E. 2000. "Comparison of Two Population Sampling Methods Used in Field Life History Studies of Mesovelia Mulsanti (Heteroptera: Gerromorpha: Mesoveliidae) in Southern Illinois," The Great Lakes Entomologist, vol 33 (3) Available at: https://scholar.valpo.edu/tgle/vol33/iss3/8 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. -2000 THE GREAT LAKES ENTOMOLOGIST 223 COMPARISON OF TWO POPULATION SAMPLING METHODS USED IN FiElD LIFE HISTORY STUDIES OF MESOVEUA MULSANTI [HETEROPTERA: GERROMORPHA: MESOVELIIDAEj IN SOUTHERN ILLINOIS Sleven J. Taylor1 and J. E. McPherson2 ABSTRACT A field life history study of Mesovelia mulsanti was conducted in south­ern Illinois, the results of which are compared with those from an earlier study also conducted in southern Illinois. The tw  studies differed in the collecting techniques used (quadrat sampler versus aquatic net). Results of the present study give a clearer picture of the life history of this insect be­cause the quadrat sampler collected representative samples of nymphs and adults more effectively than the aquatic net and, thus, the quadrat samples more accurately represented the actual chronology of the annual genera­tions. The water treader Mesovelia mulsanti White occurs from Newfound­land, Nova Scotia, New Brunswick (Scudder 1987), New York, and Massa­chusetts south to Florida, and west to British Columbia and California; it also has been reported from Mexico to Argentina, the West Indies, and the Hawaiian Islands (Smith 1988). It occurs throughout much of Illinois (Tay­lor 1996). Mesovelia mulsanti is epipleustonic, inhabiting shaded and unshaded areas, especially standing water with duckweed and algae (McPherson 1988, Taylor 1996). It is predaceous, feeding primarily on insects on the water sur­face and, possibly, on small orga isms that come to the surface from below (McPherson 1988). This insect's life history has been studied in southern Illinois (Gal­breath 1973, 1975, 1976a, 1976b; McPherson 1988) and elsewhere (e.g., Hoffmann 1932; Hungerford 1917, 1920; Lanciani 1987). However, there is some question about the number of generations per year. In southern Illi­nois, for example, Galbreath (1973, 1975) stated that this species has five and possibly more generations per year, whereas McPherson (1988) found only three generations and a partial fourth, with eggs apparently overwin­tering. McPherson's (1988) field study was conducted in the La Rue-Pine Hills Ecological Area (now La Rue-Pine Hills Research Natural Area) in Union lCenter for Biodiversity, Illinois Natural History Survey, 607 East Peabody Drive, Champaign, Illinois 61820-6970. 2Department of Zoology, Southern Illinois University at Carbondale, Carbondale, Illinois 62901-6501. 1Taylor and McPherson: Comparison of Two Population Sampling Methods Used in Field LifePublished by ValpoScholar, 2000224 THE GREAT LAKES ENTOMOLOGIST Vol. 33, No.3 &4 County from 1983 to 1986. Specimens were collected with a 0.33 m-wide aquatic net at approximately weekly intervals during the active season (April to November). Data from the four years were combined to gain a better understanding of the annual life cycle. However, there is some question about the reliability of his data because of problems inher nt in the use of an aquatic net (i.e., smaller specimens are more likely to b  overlooked) and be­cause the study was part of a larger qualitative study of both the semi­aquatic and aquatic Heteroptera. For this larger study, sweeps collected ma­terial below and on the surface of the water simultaneously and included aquatic vegetation, detritus, and insects. There was no attempt to limit sweeps to the surface of the water and, therefore, detecting the earlier in­stars of M. mulsanti (1st instars averaged less than 1.00 mm in length [un­published data]) in samples containing much organic debris was difficult. As would be expected, the number of adults collected represented an artificially high percentage of the total number of individuals collected during the study (2,239/5,092; 44%). This paper results from a larger study of the biology of the Gerrom rpha in Illinois (Taylor 1996). As a part ofthat project, we studied the life histories and microhabitat distributions of several species (including M. mulsanti) during 1989 and 1990 at President's Pond on the campus of Southern Illinois University at Carbondale, Jackson County, Illinois. President's Pond is roughly triangular, with a surface area of approximately 0.29 hectare (0.72 acre) (see Taylor [1996] and Taylor and McPherson [1998a, 1998b, 1999] for detailed description of pond). The collecting technique for President's Pond was designed s cally to sample all gerromorphan instars, regardless of size. Because erson's (1988) study was conducted only 25 km southwest of President's Pond, we were able to compare our results and collecting techniques with his. There­fore, the purposes o  this paper are to present the results of our study of the annual life cycle of M. mulsanti at President's Pond, compare the efficacy of the collecting technique with that ofMcPherson (1988) for sampling nymphal and adult stages, and examine the influence of these techniques on our abil­ity to distinguish between generations. MATERIALS AND METHODS Samples were collected weekly from 18 March to 25 November 1989 and, because of overcollecting in 1989, biweekly from 11 February to 2 December 1990. Sampling was limited to an area along the eastern shore because (1) the cattails along the western shoreline prevented use of the quadrat sam­pler (see below); (2) the riprap shoreline of the southern border was unnat­ural and, often, disturbed by fishermen; and (3) the water surface along the eastern shore, which was a mosaic of open water, duckweeds, and emlerlzerlt stems, supported a diverse gerromorphan fauna. Four 60 m transects were made parallel to a relatively uniform section of the eastern margin at 0, 0.5, 1.0, and 1.5 m from the shoreline. Each sample wascollected with a floating quadrat sampler (0.25 x 0.25 x 0.05 m) (see Taylor 1996), with four eplicates placed randomly along each transect; the resulting 16 quadrat samples were pooled, providing a br ad sampling of the habitat. Prior to each sample, the collector (SJT) stood for approxi­mately 3 minutes to a low the insects to acclima e to the disturbance; then, the sampler was placed on the surface of the water. Epipluestonic arthro­pods were removed with a fine mesh nylon net (0.42 mm diam. mesh open­ings), preserved in alcohol, and sorted in the laboratory by instar, and, ad­2The Great Lakes Entomologist, Vol. 33, No. 3 [2000], Art. 8https://scholar.valpo.edu/tgle/vol33/iss3/8-2000 225THE GREAT LAKES ENTOMOLOGIST Figure 1. Percent of individuals in each stage per sample of Mesovelia mul­santi collected at President's Pond, Southern Illinois University at Carbon­dale campus, Jackson County, during 1989. Beginning and end points of each shaded area represent sample dates preceding and following collection of specimens, respectively. ditionally for 5th instars and adults, by sex and wing morph (apterous and macropterous). Galbreath's (1975) intermediate morph was not distin­guished from the apterous morph in our study. Nymphal instars were dis­tinguished by tergal and genitalic features (see McPherson and Taylor 1993). RESULTS AND DISCUSSION Mesovelia mulsanti apparently overwinters as eggs. Combining data from 1989 and 1990, first instars were found from late April through mid­September, second i stars from mid-April through late September, third in­stars from late April through late September, fourth instars from late April 3Taylor and McPherson: Comparison of Two Population Sampling Methods Used in Field LifePublished by ValpoScholar, 2000226 THE GREAT LAKES ENTOMOLOGIST Vol. 33, No.3 &4 2 2 2 <ii'" -5 2.s: '5 E '0 2 C ~ Ql 2 a. 2 50 50 5 ADULT a (N=214) 5 )-5 50 1ST a INSTAR 5 (N=536) )-5 50 2ND a INSTAR 5 (N=419) 1-50 5-3RD a INSTAR 5 (N=213) 501-5 4TH a INSTAR 5 (N=127) 501-5 5TH a INSTAR 5 (N=117) MAR APRIL MAY JUNE JULY AUG SEPT. OCT NOV. .... t--.. ...~-..... ...-... --_._. "-r-""'" ..... --...............---- ---.....--........... ~ r-----r-'1 Figure 2. Percent in each sample of total individuals of same stage of Mesovelia mulsanti collected at President's Pond, Southern Illinois Univer­sity at Carbondale campus, Jackson County, during 1989. Beginning and end points of each shaded area represent sample dates preceding and following collection of specimens, respectively. through late September, fifth instars from late April through late September, and adults from early May through early November (Figs. 1-4). The number of generations per year was difficult to determine although apparently there were four or five. Hoffmann (1932), under uncontrolled lab­oratory conditions, reported nymphal development averaged 20.02 days; whereas Lanciani (1987), under controlled conditions (28oC, 12L:12D pho­toperiod), reported it averaged 13.38 days. Because these insect  are active from April to November in Illinois (McPherson 1988, Taylor 1996), and devel­opmental time varies with changes in temperature (Galbreath 1975), the short generation time reported by Lanciani (1987) suggests that the active season is of sufficient length to allow four or five generations per year in southern Illinois. McPherson (1988) reported three generations and a partial fourth. Al­4The Great Lakes Entomologist, Vol. 33, No. 3 [2000], Art. 8https://scholar.valpo.edu/tgle/vol33/iss3/8r 2000 THE GREAT LAKES ENTOMOLOGIST 227 (/) 0; :::J ~ '6 .£: '0 1: <ll f::' <ll a. r Figure 3. Percent of individuals in each stage per sample of Mesovelia muZ­santi collected at President's Pond, Southern Illinois University at Carbon­dale campus, Jackson County, during 1990. Beginning and end points of each shaded area represent sample dates preceding and following collection of specimens, respectively. though it might seem that his study would have been more thorough because it was conducted over four years rather than two, voltinism was determined by combining the data across all years int  a single year because the num­bers of early instars were low. In addition, sample dates varied slightly from year to year, and, therefore, samples from the four years were lumped into weekly samples (JEM, unpublished data). Therefore, it is likely that the peaks corresponding to generations were obscured. As discussed earlier, McPherson (1988) collected aquati  and semiaquatic Heteroptera with an aquatic net, whereas the present study used a quadrat sampler. Because sampling was limited to the epipleuston in the present study, samples were relatively free of organic debris compared to those col­lected in McPherson's (1988) study. Comparisons of the numbers of nymphal instars and the adults showed that the quadrat sampler collected representa­5Taylor and McPherson: Comparison of Two Population Sampling Methods Used in Field LifePublished by ValpoScholar, 2000228 THE GREAT LAKES ENTOMOLOGIST Vol. 33, No.3 & 4 Figure 4. Percent in each sample of total individuals of same stage of Mesovelia mulsanti collected at President's Pond, Southern Illinois Univer­sity at Carbondale campus, Jackson County, 1990. Beginning and e d points of each shaded area represent sample dates preceding and following collection of specimens, respectively. tive samples of al  stages more effectively than the aquatic net (Fig. 5). Al­though the results of the present study were not dramatically different from those of McPherson (1988), the quadrat samples more accurately present the actual chronology of the annual generations and provide higher confi­dence in our conclusions. ACKNOWLEDGMENTS We thank R. E. DeWalt and M. J. Wetzel, Illinois Natural History Survey, for their critical reviews. R A. Brandon, J. A. Beatty, B. M. Burr, Department of Zoology; and D. Ugent, Department of Plant Biology, Southern Illinois University at Carbondale, reviewed an arlier version of this manuscript. 6The Great Lakes Entomologist, Vol. 33, No. 3 [2000], Art. 8https://scholar.valpo.edu/tgle/vol33/iss3/82000 229THE GREAT LAKES ENTOMOLOGIST A B Adult 5th Instar 4th Instar 3rd Instar 2 d Instar 1 Instar Figure 5. Life stage distribution (percent of individuals) for MesoveZia muZ­santi. A-specimens collected with quadrate sampler in 1989 at President's Pond, Southern Illinois University at Carbondale campus, Jackson County. B-specimens collected with aquatic net from 1983 to 1986 at La Rue-Pine Hills Research Natural Area, Union County (McPherson 1988). LITERATURE CITED Galbreath, J. E. 1973. Diapause in Mesouelia mulsanti (Hemiptera: Mesoveliidae). J. Kansas Entomol. Soc. 46: 224-233. Galbreath, J. E. 1975. Thoracic polymorphism in Mesouelia mulsanti (Hemiptera: Mesoveliidae). Univ. Kansas Sci. Bull. 50: 457-482. Galbreath, J. E. 1976a. The effect of th  age of the female on diapause in Mesouelia mulsanti (Hemiptera: Mesoveliidae). J. Kansas Entomol. Soc. 49: 27-3l. Galbreath, J. E. 1976b. Reproduction in Mesouelia mulsanti (Hemiptera: Mesoveli­idae). Trans. Illinois State Acad. Sci. 69: 91-99. Hoffmann, C. H. 1932. The biology of three North American species of Mesouelia (Hemiptera-Mesoveliidae). Can. Entomol. 64: 88-95,113-120,126-134. Hungerford, H. B. 1917. The life-history of Mesouelia mulsanti White. Psyche 24: 73-84. Hungerford, H. B. 1920. The biology and ecology of aquatic and s miaquatic Hemiptera. Univ. Kansas Sci. Bull. 11: 3-328 (1919). Lanciani, C. A. 1987. Rearing immature Mesouelia mulsanti (Hemiptera: Mesoveliidae) on a substratum of duckweed. Fla. Entomol. 70: 286-288. McPherson, J. E. 1988. Life history of Mesouelia mulsanti (Hemiptera: Mesoveliidae) in southern Illinois. Great Lakes Entomol. 21: 19-23. McPherson, J. E. and S. J. Taylor. 1993. Distinguishing nymphal instars of Mesouelia mulsanti (Heteroptera: Mesoveliidae). Great Lakes Entomol. 26: 233-236. Scudder, G. G. E. 1987. Aquatic and semiaquatic Hemiptera of peatlands and marshes in Canada. Mem. Entomol. Soc. Canada 140: 65-98. Smith, C. L. 1988. Family Mesoveliidae Douglas and Scott, 1867, pp. 247-248. In: T. J. Henry and R. C. Froeschner (eds.) Catalog of the Heteroptera, or true bugs, of Canada and the Continental United States. E. J. Brill, New York. Taylor, S. J. 1996. Habitat preferences, species assemblages, and resource partitioning by Gerromorpha (Insecta: Heteroptera) in southern Illinois, with a faunal list and 7Taylor and McPherson: Comparison of Two Population Sampling Methods Used in Field LifePublished by ValpoScholar, 2000230 THE GREAT LAKES ENTOMOLOGIST Vol. 33, No.3 &4 keys to species of the state. Ph.D. Dissertation, Department of Zoology, Southern Illi­nois U iversity at Carbondale. Taylor, S. J. and J. E. McPherson. 1998a. Voltinism in Neogerris hesione (Heteroptera: Gerridae) in southern Illinois. EntomoL News 109: 233-239. Taylor, S. J. nd J. E. McPherson. 1998b. Voltinism in Merragata brunnea (Het­eroptera: Gerromorpha: Hebridae) in southern minois. Fla. Entomo!. 81: 509-515. Taylor, S. J. and J. E. McPherson. 1999. Morphological variation and polyvoltinism of Microvelia pulchella (Heteroptera: Veliidae) in southern Illinois, USA. Acta Soci­etaris Zoologicae Bohemicae 63: 237-249. 8The Great Lakes Entomologist, Vol. 33, No. 3 [2000], Art. 8https://scholar.valpo.edu/tgle/vol33/iss3/8

Comparison of Two Population Sampling Methods Used in Field Life History Studies of \u3ci\u3eMesovelia Mulsanti\u3c/i\u3e (Heteroptera: Gerromorpha: Mesoveliidae) in Southern Illinois

ValpoScholar

The Great Lakes Entomologist 
Volume 33 
Numbers 3 & 4 - Fall/Winter 2000 Numbers 3 & 
4 - Fall/Winter 2000 
Article 8 
October 2000 
Comparison of Two Population Sampling Methods Used in Field 
Life History Studies of Mesovelia Mulsanti (Heteroptera: 
Gerromorpha: Mesoveliidae) in Southern Illinois 
Steven J. Taylor 
Illinois Natural History Survey 
J. E. McPherson 
Southern Illinois University 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Taylor, Steven J. and McPherson, J. E. 2000. "Comparison of Two Population Sampling Methods Used in 
Field Life History Studies of Mesovelia Mulsanti (Heteroptera: Gerromorpha: Mesoveliidae) in Southern 
Illinois," The Great Lakes Entomologist, vol 33 (3) 
Available at: https://scholar.valpo.edu/tgle/vol33/iss3/8 
This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. 
It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. 
For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 
-2000 THE GREAT LAKES ENTOMOLOGIST 223 
COMPARISON OF TWO POPULATION SAMPLING METHODS USED IN 

FiElD LIFE HISTORY STUDIES OF MESOVEUA MULSANTI 

[HETEROPTERA: GERROMORPHA: MESOVELIIDAEj 

IN SOUTHERN ILLINOIS 

Sleven J. Taylor1 and J. E. McPherson2 
ABSTRACT 
A field life history study of Mesovelia mulsanti was conducted in south­
ern Illinois, the results of which are compared with those from an earlier 
study 
also 
conducted in southern Illinois. The tw  studies differed in the 
collecting techniques used (quadrat sampler versus aquatic net). Results of 
the present study 
give a 
clearer picture of the life history of this insect be­
cause the quadrat sampler 
collected 
representative samples of nymphs and 
adults more 
effectively 
than the aquatic net and, thus, the quadrat samples 
more accurately represented the actual 
chronology 
of the annual genera­
tions. 
The water treader Mesovelia mulsanti White occurs from Newfound­
land, Nova 
Scotia, 
New Brunswick (Scudder 1987), New York, and Massa­
chusetts south 
to 
Florida, and west to British Columbia and California; it 
also has been reported from Mexico to Argentina, the West Indies, and the 
Hawaiian Islands (Smith 
1988). 
It occurs throughout much of Illinois (Tay­
lor 1996). 
Mesovelia mulsanti is epipleustonic, inhabiting shaded and unshaded 
areas, 
especially 
standing water with duckweed and algae (McPherson 1988, 
Taylor 1996). It is predaceous, feeding primarily on insects on the water sur­
face and, possibly, on small orga isms that come to the surface from below 
(McPherson 1988). 
This insect's 
life 
history has been studied in southern Illinois (Gal­
breath 
1973, 1975, 
1976a, 1976b; McPherson 1988) and elsewhere (e.g., 
Hoffmann 
1932; 
Hungerford 1917, 1920; Lanciani 1987). However, there is 
some question about the number of generations per year. In southern Illi­
nois, for example, Galbreath (1973, 1975) stated that this species has five 
and 
possibly 
more generations per year, whereas McPherson (1988) found 
only three generations and a partial fourth, with eggs apparently overwin­
tering. 
McPherson's (1988) field 
study was conducted in the La Rue-Pine Hills 
Ecological Area (now La Rue-Pine Hills Research Natural Area) in Union 
lCenter for Biodiversity, Illinois Natural History Survey, 607 East Peabody Drive, 
Champaign, 
Illinois 
61820-6970. 
2Department of Zoology, Southern Illinois University at Carbondale, Carbondale, 
Illinois 62901-6501. 
1
Taylor and McPherson: Comparison of Two Population Sampling Methods Used in Field Life
Published by ValpoScholar, 2000
224 THE GREAT LAKES ENTOMOLOGIST Vol. 33, No.3 &4 
County from 1983 to 1986. Specimens were collected with a 0.33 m-wide 
aquatic net at approximately weekly intervals during the active season 
(April to November). 
Data from the four years were combined to gain a better 
understanding of the annual 
life cycle. However, 
there is some question 
about the 
reliability 
of his data because of problems inher nt in the use of an 
aquatic net 
(i.e., 
smaller specimens are more likely to b  overlooked) and be­
cause the study was part of 
a 
larger qualitative study of both the semi­
aquatic and aquatic Heteroptera. For this larger 
study, sweeps collected 
ma­
terial 
below 
and on the surface of the water simultaneously and included 
aquatic vegetation, detritus, and insects. There was no attempt to limit 
sweeps to 
the surface of the water and, therefore, detecting the earlier in­
stars of M. mulsanti (1st instars averaged less than 1.00 mm in length [un­
published 
data]) 
in samples containing much organic debris was difficult. As 
would be expected, the number of adults collected represented an artificially 
high percentage of the total number of individuals 
collected 
during the study 
(2,239/5,092; 44%). 
This paper results from a larger study of the biology of the Gerrom rpha 
in Illinois (Taylor 1996). As a part ofthat project, we studied the life histories 
and microhabitat distributions of several 
species 
(including M. mulsanti) 
during 
1989 
and 1990 at President's Pond on the campus of Southern Illinois 
University at Carbondale, Jackson County, Illinois. President's Pond is 
roughly 
triangular, with a surface area of approximately 0.29 hectare (0.72 
acre) (see Taylor [1996] and Taylor and McPherson [1998a, 1998b, 1999] for 
detailed 
description 
of pond). 
The 
collecting 
technique for President's Pond was designed s cally to 
sample all gerromorphan instars, regardless of size. Because erson's 
(1988) study was conducted only 25 km southwest of President's Pond, we 
were 
able to compare 
our results and collecting techniques with his. There­
fore, the purposes o  this paper are to present the results of our study of the 
annual 
life cycle 
of M. mulsanti at President's Pond, compare the efficacy of 
the 
collecting 
technique with that ofMcPherson (1988) for sampling nymphal 
and adult 
stages, 
and examine the influence of these techniques on our abil­
ity 
to 
distinguish between generations. 
MATERIALS AND METHODS 
Samples 
were collected weekly from 18 
March to 25 November 1989 and, 
because of overcollecting in 1989, biweekly from 11 February to 2 December 
1990. Sampling was limited to an area along the eastern shore because (1) 
the cattails 
along 
the western shoreline prevented use of the quadrat sam­
pler 
(see below); (2) 
the riprap shoreline of the southern border was unnat­
ural and, 
often, 
disturbed by fishermen; and (3) the water surface along the 
eastern 
shore, which 
was a mosaic of open water, duckweeds, and emlerlzerlt 
stems, supported 
a diverse 
gerromorphan fauna. 
Four 
60 m 
transects were made parallel to a relatively uniform section 
of the eastern margin at 
0, 0.5, 1.0, 
and 1.5 m from the shoreline. Each 
sample was
collected 
with a floating quadrat sampler (0.25 x 0.25 x 0.05 m) 
(see Taylor 1996), with four eplicates placed randomly along each transect; 
the resulting 
16 
quadrat samples were pooled, providing a br ad sampling 
of the habitat. Prior to each sample, the 
collector (SJT) stood for approxi­mately 
3 
minutes to a low the insects to acclima e to the disturbance; then, 
the sampler was placed 
on 
the surface of the water. Epipluestonic arthro­
pods were removed with a fine mesh nylon net (0.42 mm diam. mesh open­
ings), preserved in alcohol, and sorted in the laboratory by instar, and, ad­
2
The Great Lakes Entomologist, Vol. 33, No. 3 [2000], Art. 8
https://scholar.valpo.edu/tgle/vol33/iss3/8
-

2000 225THE GREAT LAKES ENTOMOLOGIST 
Figure 1. Percent of individuals in each stage per sample of Mesovelia mul­
santi collected at President's Pond, Southern Illinois University at Carbon­
dale campus, Jackson County, during 1989. Beginning and end points of each 
shaded area represent sample dates preceding and 
following collection 
of 
specimens, respectively. 
ditionally 
for 
5th instars and adults, by sex and wing morph (apterous and 
macropterous). Galbreath's 
(1975) 
intermediate morph was not distin­
guished 
from 
the apterous morph in our study. Nymphal instars were dis­
tinguished by tergal and genitalic features (see McPherson and Taylor 
1993). 
RESULTS AND 
DISCUSSION 
Mesovelia mulsanti apparently overwinters as eggs. Combining data 
from 1989 and 1990, first instars were found from late April through mid­
September, second i stars from mid-April through late September, third in­
stars 
from 
late April through late September, fourth instars from late April 
3
Taylor and McPherson: Comparison of Two Population Sampling Methods Used in Field Life
Published by ValpoScholar, 2000
226 THE GREAT LAKES ENTOMOLOGIST Vol. 33, No.3 &4 
2 
2 
2 
<ii'" 
-5 2
.s: 
'5 
E 
'0 2 

C 

~ 
Ql 2 
a. 
2 
50 
50 
5 
ADULT 
a (N=214) 
5 
)-
5 
50 
1ST 
a INSTAR 
5 (N=536) 
)-
5 
50 
2ND 
a INSTAR 
5 
(N=419) 
1-50 
5-
3RD 
a INSTAR 
5 (N=213) 
501-
5 
4TH 
a INSTAR 
5 (N=127) 
501-
5 
5TH 
a INSTAR 
5 (N=117) 
MAR APRIL MAY JUNE JULY AUG SEPT. OCT NOV. 
.... t--
.. ...~-
..... 
...-... 
--_._. 
"-r-""'" 
..... 
--
.........
......---
- --
-
.....-
-
........... 
~ r---
--
r-
'1 
Figure 2. Percent in each sample of total individuals of same stage of 
Mesovelia mulsanti collected at President's Pond, Southern Illinois Univer­
sity at Carbondale campus, Jackson 
County, 
during 1989. Beginning and end 
points of each shaded area represent sample dates preceding and 
following 
collection 
of specimens, respectively. 
through late September, 
fifth 
instars from late April through late September, 
and adults from early May through early November 
(Figs. 
1-4). 
The number of generations per year was 
difficult 
to determine although 
apparently there were four or 
five. 
Hoffmann (1932), under uncontrolled lab­
oratory conditions, reported nymphal development averaged 20.02 days; 
whereas Lanciani 
(1987), 
under controlled conditions (28oC, 12L:12D pho­
toperiod), reported it averaged 13.38 days. Because these insect  are active 
from April to November in Illinois (McPherson 1988, Taylor 1996), and devel­
opmental time varies with changes in temperature (Galbreath 
1975), 
the 
short generation time reported by Lanciani 
(1987) 
suggests that the active 
season is of sufficient length to allow four or 
five 
generations per year in 
southern 
Illinois. McPherson 
(1988) 
reported three generations and a partial fourth. Al­
4
The Great Lakes Entomologist, Vol. 33, No. 3 [2000], Art. 8
https://scholar.valpo.edu/tgle/vol33/iss3/8
r 

2000 THE GREAT LAKES ENTOMOLOGIST 227 
(/) 
0; 
:::J 
~ 
'6 
.£: 
'0 
1: 
<ll 
f::' 
<ll 
a. r 
Figure 3. Percent of individuals in each stage per sample of Mesovelia muZ­
santi collected at President's Pond, Southern Illinois University at Carbon­
dale campus, Jackson County, during 1990. Beginning and end points of each 
shaded area represent sample dates preceding and 
following collection 
of 
specimens, respectively. 
though it might seem that his study 
would 
have been more thorough because 
it was 
conducted over four 
years rather than two, voltinism was determined 
by 
combining 
the data across all years int  a single year because the num­
bers of early instars were low. In 
addition, 
sample dates varied slightly from 
year 
to year, and, therefore, 
samples from the four years were lumped into 
weekly samples (JEM, unpublished data). Therefore, it is likely that the 
peaks 
corresponding to 
generations were obscured. 
As discussed earlier, McPherson (1988) collected aquati  and semiaquatic 
Heteroptera with an aquatic net, whereas the present study used 
a 
quadrat 
sampler. Because sampling was limited to the epipleuston in the present 
study, 
samples were relatively free of organic debris compared to those col­
lected in McPherson's (1988) study. Comparisons of the numbers of nymphal 
instars and the adults 
showed 
that the quadrat sampler collected representa­
5
Taylor and McPherson: Comparison of Two Population Sampling Methods Used in Field Life
Published by ValpoScholar, 2000
228 THE GREAT LAKES ENTOMOLOGIST Vol. 33, No.3 & 4 
Figure 4. Percent in each sample of total individuals of same stage of 
Mesovelia mulsanti collected at President's Pond, Southern Illinois Univer­
sity at 
Carbondale campus, 
Jackson County, 1990. Beginning and e d 
points of each shaded area represent sample dates preceding and following 
collection of specimens, respectively. 
tive samples of al  stages more effectively than the aquatic net (Fig. 5). Al­
though the results 
of 
the present study were not dramatically different from 
those of McPherson (1988), the quadrat samples more accurately present 
the actual 
chronology of 
the annual generations and provide higher confi­
dence in our conclusions. 
ACKNOWLEDGMENTS 
We thank 
R. E. DeWalt 
and M. J. Wetzel, Illinois Natural History Survey, 
for their critical reviews. R A. Brandon, J. A. Beatty, B. M. Burr, Department 
of 
Zoology; 
and D. Ugent, Department of Plant Biology, Southern Illinois 
University at Carbondale, reviewed an arlier version of this manuscript. 
6
The Great Lakes Entomologist, Vol. 33, No. 3 [2000], Art. 8
https://scholar.valpo.edu/tgle/vol33/iss3/8
2000 229THE GREAT LAKES ENTOMOLOGIST 
A B 

Adult 
5th Instar 
4th 
Instar 3rd 
Instar 2 d 
Instar 
1
 Instar 
Figure 5. Life stage distribution (percent of individuals) for MesoveZia muZ­
santi. A-specimens collected with quadrate sampler in 1989 at President's 
Pond, Southern Illinois University at Carbondale campus, Jackson County. 
B-specimens 
collected 
with aquatic net from 1983 to 1986 at La Rue-Pine 
Hills Research Natural Area, Union County (McPherson 1988). 
LITERATURE CITED 
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1975. 
Thoracic polymorphism in Mesouelia mulsanti (Hemiptera: 
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mulsanti (Hemiptera: Mesoveliidae). J. Kansas Entomol. Soc. 49: 27-3l. 
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1976b. 
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keys to species of the state. Ph.D. Dissertation, Department of Zoology, Southern Illi­
nois U iversity at Carbondale. 
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Comparison of Two Population Sampling Methods Used in Field Life History Studies of \u3ci\u3eMesovelia Mulsanti\u3c/i\u3e (Heteroptera: Gerromorpha: Mesoveliidae) in Southern Illinois

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