Adults and late-instar nymphs of the wide-ranging myrmecomorphic lygaeid Slaterobius insignis were collected in northern Minnesota from cracks of granite outcrops and ledges, a habitat differing somewhat from that reported elsewhere. At two of the four sites, S. insignis was observed in plant-and litter-filled cracks with nymphs of the lygaeid Trapezonotus arenarius. All adults of the polymorphic S. insignis observed on granite were brachypters that belonged to the dark color morph of the species. Individuals occurred on rock surfaces with a black ant, Formica subsericea, which they resembled in appearance and behavior

Wheeler, A. G, Jr.

English

ValpoScholar

The Great Lakes Entomologist 
Volume 28 
Numbers 3 & 4 -- Fall/Winter 1995 Numbers 3 & 
4 -- Fall/Winter 1995 
Article 4 
January 1995 
Slaterobius Insignis (Heteroptera: Lygaeidae): Association With 
Granite Ledges and Outcrops in Minnesota 
A. G. Wheeler Jr. 
Pennsylvania Department of Agriculture 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Wheeler, A. G. Jr. 1995. "Slaterobius Insignis (Heteroptera: Lygaeidae): Association With Granite Ledges 
and Outcrops in Minnesota," The Great Lakes Entomologist, vol 28 (3) 
Available at: https://scholar.valpo.edu/tgle/vol28/iss3/4 
This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. 
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1995 213THE GREAT LAKES ENTOMOLOGIST 
SLATEROBIUS INSIGNIS (HETEROPTERA: LYGAEIDAE): ASSOCIATION 

WITH GRANITE LEDGES AND OUTCROPS IN MINNESOTA 

A. G. Wheeler, Jr. 1 
ABSTRACT 
Adults and late-instar nymphs of the wide-ranging myrmecomorphic ly­
gaeid Slaterobius insignis were collected in northern Minnesota from cracks 
of granite 
outcrops 
and ledges, a habitat differing somewhat from that re­
ported elsewhere. At two of the four sites, S. ins ignis was observed in plant­
and 
litter-filled cracks 
with nymphs of the lygaeid Trapezonotus arenarius. All 
adults 
of 
the polymorphic S. insignis observed on granite were brachypters 
that 
belonged 
to the dark color morph of the species. Individuals occurred on 
rock surfaces with a black ant, Formica subsericea, which they resembled in 
appearance and 
behavior. 
The myrmecomorphic lygaeid 
Slaterobius insignis (Uhler) belongs to the 
large subfamily Rhyparochrominae, tribe Myodochini. Formerly placed in the 
genus Sphaerobius (see Harrington 1980), this wide-ranging species is known 
from Newfoundland and Nova Scotia west to British Columbia, Alaska, the 
Northwest Territories, and the Yukon Territory so th to New York, Iowa, Col­
orado, California, Texas, and Mexico (Slater 1964, Ashlock & Slater 1988, 
Scudder 1993, Slater et al. 1993). Its occurrence in the Northeast is thought 
to represent range expansion from we tern North America (Sweet 1964, 
Slater et aI. 1993). 
Habitat 
preferences 
are known only for a portion of this seed bug's exten­
sive range. In Connecticut and the Adirondacks of New York it occurs among 
clumps of little bluestem (Schizachrium scoparium) in open, xeric sites, in­
cluding railroad rights-of-way and roadsides. In these hot, barren areas this 
bivoltine lygaeid s associated with ants and feeds on fallen seeds of little 
bluestem and other 
grasses (Sweet 1964). 
The 
habitat reported for Nova Scotia is similar-a south-facing sandy 
slope (Scudder 1993)-but the habitat in Newfoundland differs by being wet­
ter: open, swampy ground harboring colonies of Carex and Sphagnum (Lind­
berg 1958). In the Midwest, S. nsignis inhabits climax prairie dominated by 
Andropogon (or Schizachrium) and Stipa (Hendrickson 1930). In western 
Canada it 
occurs 
in "Mixed Prairie, Tallgrass prairie, and Fescue Grasslands" 
of the Prairie 
Provinces; 
in British Columbia it has been collected in the 
Pacific Northwest Bunchgrass ecosystem. Habitats in the Yukon include 
south-facing slopes characterized by Festuca grasslands and Artemisia (Scud­
der 
1993).
Sweet (1964) noted 
that fieldwork throughout the range of S. insignis was 
needed. Herein, I describe the sites where this lygaeid was observed in Min­
nesota, an area from which habitat preferences remain unrecorded. Notes are 
given on wing condition and color forms f this polymorphic species. 
lBureau of Plant Industry, Pennsylvania Department of Agriculture, Harrisburg, 
PA 17110. 
1
Wheeler: Slaterobius Insignis (Heteroptera: Lygaeidae): Association
Published by ValpoScholar, 1995
214 THE GREAT LAKES ENTOMOLOGIST Vol. 28, No.3 &4 
COLLECTION SITES AND OBSERVATIONS 
All collections were made by the author in northern Minnesota during 
25-27 June 
1995. 1. Lake of the 
Woods Co., 
granite ledges (Fig.l) above Rapid River, east
edge of Clementson; 4 adults and 2 late-instar nymphs in crevices with a thin 
layer of pine needles (Pinus strobus) and white pine "flowers" (microsporan­
giate strobili). 
2. 
Koochiching Co., Wayside Rest, Rt. 11, 3 mi. 
W. of Indus; 1 adult from 
granite outcropnear Rainy River; in crack filled with moss, lichens, and 
grasses. 
3. Koochiching Co., Tilson Bay, Rainy Lake; 5 adults, 1 fifth-instar nymph 
from grass-filled crevices of g an t outcrop. 
4. Lake Co., Bayside Park, Silver Bay; 9 adults, 1 fifth instar on gra ite 
cliffs along shore of Lake Superior; in cracks dominated by Potentilla triden­
tata (Fig.2) with occasional grass tufts. 
DISCUSSION 
The habitats ofS. insignis observed in Minnesota-cracks and crevices of 
extensive granite outcrops and ledges-have not been reported in othe areas 
of 
its range. Collection sites 
are somewhat similar, though, t many of those 
Sweet (1964) reported for New England-that is, open and xeric. 
Figure 1. Granite ledges in Lake of the Woods Co., Minn., where S. insignis 
was found under white pine needles. 
2
The Great Lakes Entomologist, Vol. 28, No. 3 [1995], Art. 4
https://scholar.valpo.edu/tgle/vol28/iss3/4
1995 THE GREAT LAKES ENTOMOLOGIST 215 
Figure 2. Granite outcrop in Nova Scotia with Potentilla tridentata. Habitat 
is similar to that in Minnesota where S. insignis occurred in cracks colonized 
by the same plant species. 
Individuals of S. insignis were occasionally seen running over the granite 
surface near plant-and litter-filled cracks, where they resembled coexisting 
black ants in their appearance and behavior. But t e lygaeid was typically de­
tected only by scratching accumulated litter, which caused the bugs to leave 
the 
cracks 
and run onto the rock. The ant species observed at the Lake County 
site (no. 4) was F rmica subsericea Say. At sites 1 and 3, late-instar nymphs 
of another rhyparochromine co-occurred with S. insignis; this gonianotine ap­
pears to be Trapezonotus arenarius (L.), a Holarctic species that in New Eng­
land is 
found mainly among sparse vegetation 
in dry, open areas of slopes 
(Sweet 1964). 
Slaterobius insignis was not encountered in cracks of smaller granite out­
crops along roadsides. Associated with these less expansive outcrops were 
adults and a few l te instars of another myodochine, Ligyrocoris sylvestris 
(L.). This species was observed in litter at the edge of these outcrops, rather 
than in 
rock cracks 
and crevices. Further sampling in Minnesota is needed to 
determine if habitats occupied by these two lygaeids are consistently distinct. 
All 19 adults of S. insignis (7 males, 12 females) collected from granite 
outcrops in Minnesota were of the nearly black (dark) morpho In some areas, 
large populations of S. ins ignis consist of nearly equal numbers of the dark 
and 
of 
the bright tan or orange-red morph (Sweet 1964, Slater et aL 1993). 
Two 
brachypterous adults of 
the light-colored morph were collected from a dif­
ferent habitat in Minnesota at about the s me time (21 June 1995); they were 
3
Wheeler: Slaterobius Insignis (Heteroptera: Lygaeidae): Association
Published by ValpoScholar, 1995
216 THE GREAT LAKES ENTOMOLOGIST Vol. 28, No.3 & 4 
swept by T. J. Henry from weeds in a gravel pit n ar Erhard, Otter Tail Co. 
All adults observed on granite outcrops were brachypterous. New England 
populations studied by Sweet (1964) were chiefly brachypterous with only 
about 20% macropterous. He remarked that it "would be interesting to see 
whether north 
midwestern populations 
in presumably widespread permanent 
habitats 
exhibit a lower frequency ofmacroptery." Although limited fieldwork in 
Minnesota 
did not yield any macropterous adults of S. insignis on granite 
outcrops, more extensive observations are needed to compare and contrast 
color and wing polymorphism of populations in thi region with those in New 
England and 
other 
parts of its range. 
Further study 
is also needed to determine 
whether S. insignis feeds 
mainly 
on seeds of grasses, 
as it does in NewEngland (Sweet 1964). It is pos­
sible that on rock outcrops the bugs are opportunists, feeding on seeds of 
grasses, Potentilla tridentata, and other plant seeds that fall or accumulate in 
cracks of the substrate. 
ACKNOWLEDGMENTS 
I thank T. J. Henry (Systematic Entomology Laboratory, USDA, c/o Na­
tional Museum of Natural History, Smithsonian Institution, Washington, DC) 
for companionship in the field, for identifying adults ofL. syluestris and S. in­
signis, and the photograph used in Fig. 1; J. A. Slater (Department of Ecology 
& Evolutionary Biology, University of Connecticut, Storrs) for identifying 
nymphs of T. arenarius; W. L. Brown, Jr. (Department of Entomology, Cornell 
University, Ithaca, NY) for identifying the ant F. subsericea; and E. R. Hoe­
beke (Department of Entomology, Cornell University) for the photograph used 
in 
Fig. 
2. 
LITERATURE CITED 
Ashlock, P. D. &A. Slater. 1988. Family Lygaeidae Schilling, 1829 (=Infericornes Amyot 
and 
Serville, 1843; Myodochidae Kirkaldy, 1899; Geocoridae Kirkaldy, 1902. pp. 167-245 in: Henry, T. J. &R. C. Froeschner (eds.), Catalog ofthe Heteroptera, or true 
bugs, of Canada and the continental United States. E. J. Brill, Leiden. 
Harrington, B. J. 1980. A generic level revision and cladistic an ly is of the Myodochini 
of the 
world (Hemiptera, Lygaeidae. Rhyparochrominae). Bull. Am. Mus. 
Nat. Hist. 
167:45-116. 
Hendrickson, G. O. 1930. Studies on the insect fauna of Iowa prairies. Iowa State ColI. 
J. Sci. 4:49-179. 
Lindberg, H. 1958. Hemiptera Heteroptera from Newfoundland, collected by the 
Swedish-Finnish expedition of 1949 and 1951. Acta Zool. Fenn 96:1-25. 
Scudder, G. G. E. 1993. Geographic distribution and biogeography of r presentative 
species of x r c grassland-adapted Nearctic Lygaeidae in western North America (In­
secta: Heteroptera). pp. 75-113 in: Ball, G. E. & H. V. Danks (eds.), Systematics and 
entomology: Diversity, distribution, adapta and application. Mem. Entomol. Soc. 
Can. 165. 
Slater, J. A. 1964. A catalogue of the Lygaeidae of the world. 2 vols. University of Con­
necticut, Storrs. 1668 pp. 
Slater, J. A., M. H. Sweet & H. Brailovsky. 1993. Two new species of Slaterobius Har­
rington with comments on the ecology and distribution of the genus (Hemiptera: Ly­
gaeidae). Proc. Entomol. Soc. Wash. 95:590-602. 
Sweet, M. H. 1964. The biology and ecology of the Rhyparochrominae of New England 
(Heteroptera: Lygaeidae). Pts I-II. Entomol. Am. 43:1-124, 44:1-201. 
4
The Great Lakes Entomologist, Vol. 28, No. 3 [1995], Art. 4
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\u3ci\u3eSlaterobius Insignis\u3c/i\u3e (Heteroptera: Lygaeidae): Association With Granite Ledges and Outcrops in Minnesota

Valparaiso University

The Great Lakes Entomologist Volume 28 Numbers 3 & 4 -- Fall/Winter 1995 Numbers 3 & 4 -- Fall/Winter 1995 Article 4 January 1995 Slaterobius Insignis (Heteroptera: Lygaeidae): Association With Granite Ledges and Outcrops in Minnesota A. G. Wheeler Jr. Pennsylvania Department of Agriculture Follow this and additional works at: https://scholar.valpo.edu/tgle Part of the Entomology Commons Recommended Citation Wheeler, A. G. Jr. 1995. "Slaterobius Insignis (Heteroptera: Lygaeidae): Association With Granite Ledges and Outcrops in Minnesota," The Great Lakes Entomologist, vol 28 (3) Available at: https://scholar.valpo.edu/tgle/vol28/iss3/4 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. 1995 213THE GREAT LAKES ENTOMOLOGIST SLATEROBIUS INSIGNIS (HETEROPTERA: LYGAEIDAE): ASSOCIATION WITH GRANITE LEDGES AND OUTCROPS IN MINNESOTA A. G. Wheeler, Jr. 1 ABSTRACT Adults and late-instar nymphs of the wide-ranging myrmecomorphic ly­gaeid Slaterobius insignis were collected in northern Minnesota from cracks of granite outcrops and ledges, a habitat differing somewhat from that re­ported elsewhere. At two of the four sites, S. ins ignis was observed in plant­and litter-filled cracks with nymphs of the lygaeid Trapezonotus arenarius. All adults of the polymorphic S. insignis observed on granite were brachypters that belonged to the dark color morph of the species. Individuals occurred on rock surfaces with a black ant, Formica subsericea, which they resembled in appearance and behavior. The myrmecomorphic lygaeid Slaterobius insignis (Uhler) belongs to the large subfamily Rhyparochrominae, tribe Myodochini. Formerly placed in the genus Sphaerobius (see Harrington 1980), this wide-ranging species is known from Newfoundland and Nova Scotia west to British Columbia, Alaska, the Northwest Territories, and the Yukon Territory so th to New York, Iowa, Col­orado, California, Texas, and Mexico (Slater 1964, Ashlock & Slater 1988, Scudder 1993, Slater et al. 1993). Its occurrence in the Northeast is thought to represent range expansion from we tern North America (Sweet 1964, Slater et aI. 1993). Habitat preferences are known only for a portion of this seed bug's exten­sive range. In Connecticut and the Adirondacks of New York it occurs among clumps of little bluestem (Schizachrium scoparium) in open, xeric sites, in­cluding railroad rights-of-way and roadsides. In these hot, barren areas this bivoltine lygaeid s associated with ants and feeds on fallen seeds of little bluestem and other grasses (Sweet 1964). The habitat reported for Nova Scotia is similar-a south-facing sandy slope (Scudder 1993)-but the habitat in Newfoundland differs by being wet­ter: open, swampy ground harboring colonies of Carex and Sphagnum (Lind­berg 1958). In the Midwest, S. nsignis inhabits climax prairie dominated by Andropogon (or Schizachrium) and Stipa (Hendrickson 1930). In western Canada it occurs in "Mixed Prairie, Tallgrass prairie, and Fescue Grasslands" of the Prairie Provinces; in British Columbia it has been collected in the Pacific Northwest Bunchgrass ecosystem. Habitats in the Yukon include south-facing slopes characterized by Festuca grasslands and Artemisia (Scud­der 1993).Sweet (1964) noted that fieldwork throughout the range of S. insignis was needed. Herein, I describe the sites where this lygaeid was observed in Min­nesota, an area from which habitat preferences remain unrecorded. Notes are given on wing condition and color forms f this polymorphic species. lBureau of Plant Industry, Pennsylvania Department of Agriculture, Harrisburg, PA 17110. 1Wheeler: Slaterobius Insignis (Heteroptera: Lygaeidae): AssociationPublished by ValpoScholar, 1995214 THE GREAT LAKES ENTOMOLOGIST Vol. 28, No.3 &4 COLLECTION SITES AND OBSERVATIONS All collections were made by the author in northern Minnesota during 25-27 June 1995. 1. Lake of the Woods Co., granite ledges (Fig.l) above Rapid River, eastedge of Clementson; 4 adults and 2 late-instar nymphs in crevices with a thin layer of pine needles (Pinus strobus) and white pine "flowers" (microsporan­giate strobili). 2. Koochiching Co., Wayside Rest, Rt. 11, 3 mi. W. of Indus; 1 adult from granite outcropnear Rainy River; in crack filled with moss, lichens, and grasses. 3. Koochiching Co., Tilson Bay, Rainy Lake; 5 adults, 1 fifth-instar nymph from grass-filled crevices of g an t outcrop. 4. Lake Co., Bayside Park, Silver Bay; 9 adults, 1 fifth instar on gra ite cliffs along shore of Lake Superior; in cracks dominated by Potentilla triden­tata (Fig.2) with occasional grass tufts. DISCUSSION The habitats ofS. insignis observed in Minnesota-cracks and crevices of extensive granite outcrops and ledges-have not been reported in othe areas of its range. Collection sites are somewhat similar, though, t many of those Sweet (1964) reported for New England-that is, open and xeric. Figure 1. Granite ledges in Lake of the Woods Co., Minn., where S. insignis was found under white pine needles. 2The Great Lakes Entomologist, Vol. 28, No. 3 [1995], Art. 4https://scholar.valpo.edu/tgle/vol28/iss3/41995 THE GREAT LAKES ENTOMOLOGIST 215 Figure 2. Granite outcrop in Nova Scotia with Potentilla tridentata. Habitat is similar to that in Minnesota where S. insignis occurred in cracks colonized by the same plant species. Individuals of S. insignis were occasionally seen running over the granite surface near plant-and litter-filled cracks, where they resembled coexisting black ants in their appearance and behavior. But t e lygaeid was typically de­tected only by scratching accumulated litter, which caused the bugs to leave the cracks and run onto the rock. The ant species observed at the Lake County site (no. 4) was F rmica subsericea Say. At sites 1 and 3, late-instar nymphs of another rhyparochromine co-occurred with S. insignis; this gonianotine ap­pears to be Trapezonotus arenarius (L.), a Holarctic species that in New Eng­land is found mainly among sparse vegetation in dry, open areas of slopes (Sweet 1964). Slaterobius insignis was not encountered in cracks of smaller granite out­crops along roadsides. Associated with these less expansive outcrops were adults and a few l te instars of another myodochine, Ligyrocoris sylvestris (L.). This species was observed in litter at the edge of these outcrops, rather than in rock cracks and crevices. Further sampling in Minnesota is needed to determine if habitats occupied by these two lygaeids are consistently distinct. All 19 adults of S. insignis (7 males, 12 females) collected from granite outcrops in Minnesota were of the nearly black (dark) morpho In some areas, large populations of S. ins ignis consist of nearly equal numbers of the dark and of the bright tan or orange-red morph (Sweet 1964, Slater et aL 1993). Two brachypterous adults of the light-colored morph were collected from a dif­ferent habitat in Minnesota at about the s me time (21 June 1995); they were 3Wheeler: Slaterobius Insignis (Heteroptera: Lygaeidae): AssociationPublished by ValpoScholar, 1995216 THE GREAT LAKES ENTOMOLOGIST Vol. 28, No.3 & 4 swept by T. J. Henry from weeds in a gravel pit n ar Erhard, Otter Tail Co. All adults observed on granite outcrops were brachypterous. New England populations studied by Sweet (1964) were chiefly brachypterous with only about 20% macropterous. He remarked that it "would be interesting to see whether north midwestern populations in presumably widespread permanent habitats exhibit a lower frequency ofmacroptery." Although limited fieldwork in Minnesota did not yield any macropterous adults of S. insignis on granite outcrops, more extensive observations are needed to compare and contrast color and wing polymorphism of populations in thi region with those in New England and other parts of its range. Further study is also needed to determine whether S. insignis feeds mainly on seeds of grasses, as it does in NewEngland (Sweet 1964). It is pos­sible that on rock outcrops the bugs are opportunists, feeding on seeds of grasses, Potentilla tridentata, and other plant seeds that fall or accumulate in cracks of the substrate. ACKNOWLEDGMENTS I thank T. J. Henry (Systematic Entomology Laboratory, USDA, c/o Na­tional Museum of Natural History, Smithsonian Institution, Washington, DC) for companionship in the field, for identifying adults ofL. syluestris and S. in­signis, and the photograph used in Fig. 1; J. A. Slater (Department of Ecology & Evolutionary Biology, University of Connecticut, Storrs) for identifying nymphs of T. arenarius; W. L. Brown, Jr. (Department of Entomology, Cornell University, Ithaca, NY) for identifying the ant F. subsericea; and E. R. Hoe­beke (Department of Entomology, Cornell University) for the photograph used in Fig. 2. LITERATURE CITED Ashlock, P. D. &A. Slater. 1988. Family Lygaeidae Schilling, 1829 (=Infericornes Amyot and Serville, 1843; Myodochidae Kirkaldy, 1899; Geocoridae Kirkaldy, 1902. pp. 167-245 in: Henry, T. J. &R. C. Froeschner (eds.), Catalog ofthe Heteroptera, or true bugs, of Canada and the continental United States. E. J. Brill, Leiden. Harrington, B. J. 1980. A generic level revision and cladistic an ly is of the Myodochini of the world (Hemiptera, Lygaeidae. Rhyparochrominae). Bull. Am. Mus. Nat. Hist. 167:45-116. Hendrickson, G. O. 1930. Studies on the insect fauna of Iowa prairies. Iowa State ColI. J. Sci. 4:49-179. Lindberg, H. 1958. Hemiptera Heteroptera from Newfoundland, collected by the Swedish-Finnish expedition of 1949 and 1951. Acta Zool. Fenn 96:1-25. Scudder, G. G. E. 1993. Geographic distribution and biogeography of r presentative species of x r c grassland-adapted Nearctic Lygaeidae in western North America (In­secta: Heteroptera). pp. 75-113 in: Ball, G. E. & H. V. Danks (eds.), Systematics and entomology: Diversity, distribution, adapta and application. Mem. Entomol. Soc. Can. 165. Slater, J. A. 1964. A catalogue of the Lygaeidae of the world. 2 vols. University of Con­necticut, Storrs. 1668 pp. Slater, J. A., M. H. Sweet & H. Brailovsky. 1993. Two new species of Slaterobius Har­rington with comments on the ecology and distribution of the genus (Hemiptera: Ly­gaeidae). Proc. Entomol. Soc. Wash. 95:590-602. Sweet, M. H. 1964. The biology and ecology of the Rhyparochrominae of New England (Heteroptera: Lygaeidae). Pts I-II. Entomol. Am. 43:1-124, 44:1-201. 4The Great Lakes Entomologist, Vol. 28, No. 3 [1995], Art. 4https://scholar.valpo.edu/tgle/vol28/iss3/4

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\u3ci\u3eSlaterobius Insignis\u3c/i\u3e (Heteroptera: Lygaeidae): Association With Granite Ledges and Outcrops in Minnesota

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