Stoneflies - Plecoptera: Perlidae of Gunnison County, ColoradoHesperoperla pacifica
Golden Stonefly, Willow fly, Pacific Stonefly, Small golden stone, Golden stone, Big Golden stonefly(Banks 1900)
Updated 18 September 2024
TSN 102972
Habitat
Nymphs live in swift water in streams and rivers throughout the county and nation.
Life History
H. pacifica remain in the stream as a nymph for 2 or 3 years, the fancy word for that is semivoltine.
Richardson and Gaufin (1971) found that H. pacifica was primarily a carnivore while eating 88% animal and 12% plant matter. They prefer to eat mayflies (Ephemeroptera), midges (Chironomidae) and caddisflies (Trichoptera). The highest proportion of midge larve in their stomachs were found in Hesperoperla from the Taylor River. Richardson and Gaufin thought a large part of the detritus and plant matter in the guts of these animals is from the gut of their prey.
Fuller and Stewart (1977) noted this species is semivoltine and emerged from June to July in the Gunnison River at Lost Canyon Resort. First year nymph guts were 85% animal material from their first appearance in August - September through the following July. Chironomidae larve always had a high electivity and were over 60% of the gut contents in all months except May. In May Ephemeroptera nymphs showed a higher electivity. Small numbers of other aquatic insects appeared in the guts, but electivity for them was always negative. Second year nymphs also fed on animal matter (85%) in most months. They elected to eat more Trichoptera larvae in the fall and winter inspite of the fact that Chironomid larvae were abundant. By the next June-August, mature nymphs shifted back to Chironomids. H. pacifica showed a consistent negative electivity for Ephemeroptera nymphs except in May during the first year of their development. They either avoided feeding on the common Oligochaetes from July through September or did not encounter them while hunting.
Local Research Results
Small predators preyed on small prey and big predators showed a preference for medium sized prey. Size selectivity varied with predator size. Percent attacks per encounter by small predators were strongly biased towards small prey, Large stoneflies were weakly biased towards large prey. Capture success was greater and handling times were shorter with small prey compared to large prey (Allan et al 1987b).
This Hesperoperla was molting in a tributary of the East River today, 20 July 2011.
Locations Collected
Taylor River, Lake Fork of the Gunnison River, Gunnison River at the Lost Canyon Resort.
Notes
Older publications may refer to this species as Acroneuria pacifica.
Good Links
On this website:
Perlidae Introduction
Other Websites:
References
Adams,R and Simmons,D 1999 Ecological Effects of Fire Fighting Foams and Retardants. Conference Proceedings of the Australian Bushfire Conference, Albury
Allan,JD and Feifarek,BP 1988 Prey preference in stoneflies: a comparative analysis of prey vulnerability. Oecologia, 76(4), pp.496-503.
Abstract: "Laboratory feeding trials were conducted with the predaceous stonefly Hesperoperla pacifica and a number of mayfly and dipteran prey species to investigate the effects of predator size, and prey size and morphology, on the predator's success. Observations under dim red light permitted estimation of encounter rate (E/min), attack propensity (A/E), capture success (C/A) and handling time (HT). For prey of a particular species and size, HT decreased log-linearly with increasing predator size. Across all prey categories, HT increased log-linearly with increasing values of the ratio prey dry wt/predator dry wt, and differences among species appeared to be small. Overall, capture success was low, but C/A was higher for dipterans than for mayflies, especially with large H. pacifica. Predator size affected C/A when prey fell within a certain size range, but was not a detectable influence with very small or very large prey. Values of A/E of near 10% typified many predator prey combinations; however, ephemerellid mayflies suffered markedly fewer attacks, and values of A/E up to 30% were obtained with some species-size combinations. We estimated benefit to the predator first as prey wt ingested per unit time (dry wt/HT), and second by mutliplying the former term by capture success. Values increased with increasing size of the predator, and inclusion of the C/A term indicated that predators would obtain greater reward from small relative to large prey, and from dipterans relative to mayflies. However, there was little evidence that attacks were biased toward more profitable prey. We compare the relative contributions of E/min, A/E and C/A to prey choice, and discuss their applicability to predation events in nature."
Allan,JD; Flecker,AS; McClintock,NL 1987 Prey preference of stoneflies: sedentary vs mobile prey. Oikos 49(3) 323-331.
Abstract: " We investigated the effects of prey size and type (sedentary vs mobile) on prey preference in a predaceous stonefly, based on choice experiments and observations of the predator-prey interaction. We presented three size classes of black fly larvae (Prosimulium) to various sizes of the perlid stonefly Hesperoperla pacifica in laboratory experiments. Analysis by preference indices (α, ε) indicated that small predators preferred small prey, large predators preferred large prey, and H. pacifica of intermediate size exhibited a weak, non-significant trend toward preferring prey of intermediate size. These results using sedentary prey, black fly larvae, are compared to previous results using a mobile prey, the mayfly Baetis. Encounter, attack, capture rates and handling times differ as a function of predator size, prey size, and prey type. The results of preference trials generally can be predicted from differential encounter, attack and capture rates, and similar preference curves may have different underlying causes. Small H. pacifica preferred small prey, mainly due to a much higher capture success. Large H. pacifica preferred large prey, due principally to higher encounter and attack rates. Offered a choice between Baetis and Prosimulium, stoneflies exhibited lower encounter and attack rates with Prosimulium, but much higher capture success, resulting in a net preference for black fly larvae. We suggest that laboratory results for attacks, captures and handling time can reasonably be extrapolated to animals in nature, thus lending insight into preference estimates based on gut analysis. However, encounter rates inevitably are influenced by details of the laboratory design and may bear little relation to nature."
Allan,JD; Flecker,AS; McClintock,NL 1987 Prey size selection by carnivorous stoneflies. Limnology and Oceanograpy 32(4) 864-872. PDF
Abstract: "To investigate prey size preference by carnivorous stoneflies, we conducted choice experiments and directly observed predatory behavior in laboratory streams. Small, medium, and large size classes of Hesperoperla pacifica (Perlidae), small Kogotus modestus, and medium and large Megarcys signata (both of the Perlodidae) were offered an array of sizes of the mayfly Baetis as prey. Small predators displayed strong positive selection for the smallest size class of prey, and preference declined steadily with increasing prey size. Large predators displayed hump-shaped preference curves, exhibiting strongest preference for intermediate size classes of prey. Thus size selectivity was demonstrated and varied with the size class of predator.
Direct observations of encounters between predators and their prey revealed that percent attacks/ encounters by small predators was strongly biased toward small prey and by large predators was weakly biased toward large prey. Capture success always was greater and handling times shorter with small prey compared to large prey."
Banks,N 1900 New genera and species of Nearctic Neuropteroid Insects. Transactions of the American Entomological Society 26:239-259.
Described as Acroneuria pacifica.
Baumann,RW; Gaufin,AR; Surdick,RF 1977 The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society (31) 1-208. PDF
Quote from page 162: "This species is the most widely distributed stonefly species in the Rocky Mountains. Throughout its range it exibits a wide variation in size, wing length, coloration and shape of the female subgenital plate. However, in all cases studied, the aedeagus and ova are uniform. The adults emerge from April to October."
Béthoux,O 2005 Wing venation pattern of Plecoptera (Insecta: Neoptera). Illiesia, 1(9):52-81. PDF
Buchwalter,DB; Cain,DJ; Martin,CA; Xie,L; Luoma,SN; Garland,JT 2008 Aquatic insect ecophysiological traits reveal phylogenetically based differences in dissolved cadmium susceptibility. Proceedings of the National Academy of Sciences 105 24, 8321-8326.
DeWalt,R Edward; Stewart,Kenneth W (1995): Life histories of stoneflies (Plecoptera) in the Rio Conejos of southern Colorado. Great Basin Naturalist 55, 1-18. PDF
Fuller,RL and Stewart,KW 1977 The food habits of stoneflies (Plecoptera) in the Upper Gunnison River, Colorado. Environmental Entomology (6) 293-302.
Abstract: "Gut contents of 1,463 stonefly nymphs, comprising 10 species, from the Gunnison River, Colorado, were analyzed from Dec., 1974-Oct., 1975, in relation to food availability. Pteronarcella badia fed primarily on detritus and moss. Perlidae and Perlodidae mature nymphs were all carnivorous, but showed considerable seasonal-developmental shifting in diets and preference during earlier stages. Early instar Isoperla fulva nymphs were herbivore-detritivores, then gradually shifted through an omnivorous to carnivorous diet as development proceeded. Claassenia sabulosa and Hesperoperla pacifica remained carnivorous throughout development. Dominant prey groups were chironomids, mayflies and caddisflies. Horn's Coefficient of Dietary Overlap showed significance among all predator species for major food categories, but subtle mechanisms such as prey species-and size-selectivity and temporal succession provided sufficient partitioning of the abundant food resources to allow for coexistence. Large Claassenia sabulosa nymphs in August selected more mayflies after dark than in the afternoon. No behavioral selection by predacious stoneflies was indicated for the chironomids Ablabesmyia sp., Cricotopus sp., Prodiamesa sp., and Rheotanytarsus sp."
Gaufin,AR; Clubb,R and Newell,R 1974 Studies on the tolerance of aquatic insects to low oxygen concentrations. Great Basin Naturalist 34:45-59. PDF
The authors studied the acute short term tolerance of aquatic insects to low oxygen. They used the 96 hour Median Tolerance Limit. They discussed Hesperoperla pacifica as Acroneuria pacifica. The TLm96 for H. pacifica was 1.6mg/l and 14% oxygen saturation. This was the least tolerance for low oxygen among the 8 stonefly species tested.
Gersich,FM and Brusven,MA 1982 Volcanic ash accumulation and ash-voiding mechanisms of aquatic insects. Journal of the Kansas Entomological Society, 55(2) 290-296.
Abstract: "Four species of aquatic insects (Hesperoperla pacifica, Rhyacophila acropedes/R. vao, Drunella doddsi and Rhithrogena robusta) were subjected to suspended ash concentration of ca. 2000 mg/1 in laboratory streams for 48 hr. Macro- and microscopic examination revealed substantial ash accumulation on the exo-skeleton; however, acute toxicity was not noted. Ash-impacted aquatic insects placed in a clean water environment voided appreciable amounts of ash within 24 hr. We conclude that the four species studied had high short-term exposure tolerances to ash and that behavioral attributes allowed for the removal of exoskeletal ash deposits once the perturbation ceased."
Johnson,KR; Jepson,PC; Jenkins,JJ 2008 Esfenvalerate-induced case-abandonment in the larvae of the caddisfly (Brachycentrus americanus). Environmental Toxicology and Chemistry 27(2) 397-403. Abstract">PDF
Abstract: "Field-collected Brachycentrus americanus Banks (Trichoptera: Brachycentridae) larvae were used to investigate the relationship between esfenvalerate exposure and case-abandonment response, determine larval ability to construct a new case, and measure the change in predation risk to insects in rebuilt cases. We evaluated case-abandonment following four environmentally relevant esfenvalerate exposures, 0.05, 0.1, 0.2, and 0.4 µg/L; 48-h exposures to 0.2 and 0.4 µg/L (nominal) esfenvalerate both resulted in over 60% of larvae abandoning cases and were statistically indistinguishable. Propensity to engage in building behaviors was significantly diminished in 0.2 and 0.4 µg/L esfenvalerate-exposed insects that had abandoned cases, with less than 20% of exposed insects producing cases. Cases built by intoxicated larvae were characterized by a disorganized composition, and required half the pressure to crush versus cases built by nonexposed larvae. Pre-exposing case-building material to 1 µµg/L esfenvalerate also reduced the physical strength of rebuilt cases. Larvae inhabiting weaker rebuilt cases and larvae without cases were significantly more susceptible to predation by second year Hesperoperla pacifica Banks (Plecoptera: Perlidae) stonefly nymphs than those in original cases. Overall, we concluded that small behavioral responses can have profound consequences for survival of species and reveal susceptible stages in life-cycles that can be overlooked by conventional approaches to ecological risk assessment."
Kondratieff,BC and Baumann,RW 2002 A review of the stoneflies of Colorado with description of a new species of Capnia (Plecoptera: Capniidae). Transactions of American Entomological Society 128 3, 385-401.
Quote from page 395: " This extremely widespread western North American species can be collected in almost all types of streams, ranging from rheocrenes to large rivers throughout the Mountain and Plateau Provinces of Colorado."
Malison,RL; DelVecchia,AG; Woods,HA; Hand,BK; Luikart,G and Stanford,JA 2020 Tolerance of aquifer stoneflies to repeated hypoxia exposure and oxygen dynamics in an alluvial aquifer. Journal of Experimental Biology, 223(16). PDF
Malison,RL; Ellis,BK; DelVecchia,AG; Jacobson,H; Hand,BK; Luikart,G; Woods,HA; Gamboa,M; Watanabe,K and Stanford,JA 2020 Remarkable anoxia tolerance by stoneflies from a floodplain aquifer. Ecology, 101(10), p.e03127. PDF
Mangum,FA and Madrigal,JL 1999 Rotenone effects on aquatic macroinvertebrates of the Strawberry River, Utah: a five-year summary. Journal of Freshwater Ecology, 14(1), 125-135. PDF
Abstract: " Before treatment with a 3 mg/1 Noxfish (0.15 mg/1 active ingredient; rotenone) for 48 hours, benthic invertebrate communities were quantitatively sampled with a modified Surber net. Then spring, summer, and fall post-rotenone samples were taken monthly at each of four Strawberry River stations for five years. Statistical analyses of the data indicated that the application of rotenone had a significant effect on the following species density: Cinygmula sp., Pteronarcella badia, Hesperoperla pacifica, Hydropsyche sp., and Brachycentrus americanus. Thirty-three percent of the benthic invertebrate taxa at the four stations showed resistance to rotenone. Up to 100% of Ephemeroptera, Plecoptera and Trichoptera species were missing after the second rotenone application. Forty-six percent of the taxa recovered within one year, but 21% of the taxa were still missing after five years. Of the 19 taxa still missing, 47% were Trichoptera, 21% were Ephemeroptera, 16% were Plecoptera, 11% were Coleoptera, and 5% were Megaloptera. "
Martin,CA; Luoma,SN; Cain,DJ and Buchwalter,DB 2007 Cadmium ecophysiology in seven stonefly (Plecoptera) species: delineating sources and estimating susceptibility. Environmental science & technology, 41(20), pp.7171-7177. PDF
Mesick,CF and Tash,JC 1980 Effects of electricity on some benthic stream insects. Transactions of the American Fisheries Society, 109(4), pp.417-422.
Abstract: "Pulsed direct current, square-wave alternating current, alternating current, and direct current, at voltages similar to those currently in use for electrofishing, induced drift by Ameletus dissitus, Baetis spp., Cinygmula par, Hesperoperla pacifica, Psychoglypha subborealis, Hesperophylax occidentalis, and Epeorus longimanus under simulated stream conditions. Of nine species of insects shocked at these voltages, only Simulium jacumbae did not drift. There was an inverse relationship between the propensity of an individual to drift and the minimum level of voltage required to induce drift. Threshold body voltages varied among and within species at different body sizes and at different temperatures. Temporary reductions in productivity with potential loss of species will occur in areas that are electrofished so frequently that rates of insect displacement are greater than rates of insect recolonization."
Molles,MC and Pietruszka,RD 1983 Mechanisms of prey selection by predaceous stoneflies: roles of prey morphology, behavior and predator hunger. Oecologia 57(1) 25-31. Abstract
Newell,RL; Baumann,RW and Stanford,JA 2008 Stoneflies of Glacier National Park and Flathead River basin, Montana. International Advances in the ecology, zoogeography, and systematics of mayflies and stoneflies. University of California Publications in Entomology, Berkeley and Los Angeles, pp.173-186. PDF
Quote from page 176: "Stoneflies recorded from hyporheic habitats (pumped wells) included: Alloperla severa, Capnia confusa, Claassenia sabulosa, Diura knowltoni, Hesperoperla pacifica, Isocapnia crinita, I. grandis, I. integra, I. vedderensis, Isoperla fulva, Kathroperla, Paraperla frontalis, and P. wilsoni"
Palmquist,KR; Jenkins,JJ and Jepson,PC 2008 Effects of dietary esfenvalerate exposures on three aquatic insect species representing different functional feeding groups. Environmental Toxicology and Chemistry: An International Journal, 27(8), pp.1721-1727. PDF
Abstract: "Given the chemical properties of synthetic pyrethroids, it is probable that compounds, including esfenvalerate, that enter surface waters may become incorporated into aquatic insect food sources. We examined the effect of dietary esfenvalerate uptake in aquatic insects representing different functional feeding groups. We used three field-collected aquatic insect species: A grazing scraper, Cinygmula reticulata McDunnough (Ephemeroptera: Heptageniidae); an omnivorous filter feeder, Brachycentrus americanus Banks (Trichoptera: Brachycentridae); and a predator, Hesperoperla pacifica Banks (Plecoptera: Perlidae). Laboratory-cultured algae were preexposed for 24 h to esfenvalerate concentrations of 0, 0.025, 0.05, and 0.1 µg/L and provided to two C. reticulata age classes (small and final-instar nymphs). Reduction in small nymph growth was observed following three weeks of feeding on algae exposed to 0.05 and 0.1 µg/L of esfenvalerate, and the highest dietary exposure reduced egg production in final-instar nymphs. The diet for B. americanus and H. pacifica consisted of dead third-instar Chironomus tentans larvae preexposed for 24 h to esfenvalerate concentrations ranging between 0.1 and 1.0 µg/L. Consumption of larvae exposed to 0.5 to 1.0 µg/L of esfenvalerate caused case abandonment and mortality in B. americanus caddisfly larvae. Although H. pacifica nymphs readily consumed esfenvalerate-exposed larvae, no adverse effects were observed during the present study. Furthermore, no evidence of esfenvalerate-induced feeding deterrence was found in any of the species tested, suggesting that aquatic insects may not be able to distinguish between pyrethroid-contaminated and uncontaminated food sources. These findings indicate that feeding deterrence is not a factor in regulating aquatic insect dietary exposures to synthetic pyrethroids."
Peterson,MG; O’Grady,PM and Resh,VH 2017 Phylogeographic comparison of five large-bodied aquatic insect species across the western USA. Freshwater Science, 36(4), pp.823-837. PDF
Abstract: "Glacial legacy, barriers to migration, and dispersal abilities are important determinants of intraspecific genetic diversity. Genetic comparisons can elucidate the distribution of genetic variants among populations, but for many groups of organisms the concordance of population genetic structure and historical refugia among co-occurring species remains unclear. We compared phylogeographic histories of 4 stoneflies (Calineuria californica, Hesperoperla pacifica, Pteronarcys californica, and Pteronarcys princeps) and 1 caddisfly (Dicosmoecus gilvipes) across their species ranges. Study species had large body and wing sizes that suggest strong flying ability and dispersal potential. Nevertheless, riverine habitat restrictions and mating behaviors can inhibit dispersal. We used mitochondrial and nuclear gene sequences to examine population genetic structure relative to potential past and present barriers to dispersal in the western USA. North–south population genetic structure was present for each species but was more pronounced for 2 stoneflies (C. californica and P. californica) and the caddisfly. For these 3 species, phylogenies indicated concordant clades north and south of San Francisco Bay, a large, saltwater estuary in California. Basal phylogenetic nodes and regional centers of haplotype diversity suggested common historical refugia in northern California or southern Oregon, similar to that found in previous studies of salamanders. For 1 stonefly (C. californica) and the caddisfly, distinct populations in the Sierra Nevada Mountains suggested potential barriers to gene flow. The presence of population genetic structure suggests vulnerability to loss of intraspecific diversity under climate change scenarios, particularly for populations at high elevations."
Rader,Rb and Belish, TA 1999 Influence of mild to severe flow alterations on invertebrates in three mountain streams. Regulated Rivers: Research & Management. 15(4)353 - 363.
Discussing Hesperoperla pacifica among a few other critters, they comment that "some stoneflies declined or were even locally extirpated" by severe flow alterations due to dams and water abstraction of their habitat.
Richardson,JW; Gaufin,AR 1971 Food habits of some western stonefly nymphs. Transactions of American Entomological Society 97, 91-121.
Discussed as Acroneuria pacifica.
Sandberg,JB 2009 Vibrational communication (drumming) of the western nearctic stonefly genus Hesperoperla (Plecoptera: Perlidae). Illiesia 2009 5(13):146-155. PDF
Sheldon,AL 1980 Coexistence of perlid stoneflies (Plecoptera): predictions from multivariate morphometrics. Hydrobiologia, 71(1) 99-105. 1st two pages
Sheldon,AL 1999 Emergence patterns of large stoneflies (Plecoptera: Pteronarcys, Calineuria, Hesperoperla) in a Montana river. Great Basin Naturalist 59: 169-174. PDF
Shepard, WD. and Stewart KW 1983 Comparative Study of Nymphal Gills in North American Stonefly Genera and a New, Proposed Paradigm of Plecoptera Gill Evolution. Miscellaneous Publications of the Entomological Society of America 13:1-57
Illustration of nymphal osmobranchiae (gills) on page 46.
Stanford,JA and Ward,JV 1988 The hyporheic habitat of river ecosystems. Nature, 335(6185), pp.64-66. PDF
Abstract: "Contemporary river ecology is based primarily on biogeochemical studies of the river channel and interactions with shoreline vegetation, even though most rivers have extensive floodplain aquifers that are hydraulically connected to the channel. The hyporheic zone, the interstitial habitat penetrated by riverine animals, is characterized as being spatially limited to no more than a few metres, in most cases centimetres, away from the river channel1–9. However, riverine invertebrates were collected in hundreds per sample within a grid of shallow (10 m) wells located on the flood-plain up to 2 km from the channel of the Flathead River, Montana, USA. Preliminary mass transport calculations indicate that nutrients discharged from the hyporheic zone may be crucial to biotic productivity in the river channel. The strength and spatial magnitude of these interactions demonstrate an unexplored dimension in the ecology of gravel-bed rivers."
Stark,BP and Green,S 2011 Eggs of western Nearctic Acroneuriinae (Plecoptera: Perlidae).
Illiesia 2011 7(17):157-166. PDF
Stark,BP; Gaufin,AR 1976 The nearctic genera of Perlidae (Plecoptera). Miscellaneous Publications of the Entomological Society of America 10, 1-80. page 30.
Stewart,KW and Stark,BP 2002 Nymphs of North American Stonefly Genera. 2nd edition The Caddis Press, Columbus, Ohio. 510 pages.
Illustrations of nymph on page 344-345, figures 13.21-13.22
Stewart,KW and Zeigler,DD 1984 The use of larval morphology and drumming in Plecoptera systematics, and further studies of drumming behavior. Annals of Limnology, 20 (1-2):105-114.
Thorp,RA; Kondratieff,BC; Thorp,EC; Odenbeck,PB and Jarrett,MJ 2008 The life cycles of Claassenia sabulosa and Hesperoperla pacifica (Plecoptera: Perlidae) in two Colorado streams. Western North American Naturalist, 68(3) 311-318. PDF
Abstract: "We compared the life cycles of Claassenia sabulosa (Banks 1900) and Hesperoperla pacifica (Banks 1900) (Plecoptera: Perlidae) in allopatry and sympatry by studying 4 populations in 3 streams of the South Platte River Watershed, Colorado. We estimated 2-year life cycles for both C. sabulosa and H. pacifica in allopatry and sympatry. Evidence of egg diapausing and extended larval recruitment was noted for both species in allopatry and sympatry. There were no apparent differences in larval growth, larval recruitment, or adult emergence periodicity between allopatric and sympatric populations of C. sabulosa. In contrast, allopatric and sympatric H. pacifica populations exhibited differences in the timing of larval growth, larval recruitment, and adult emergence. We feel that the differences in the life cycles of these populations were likely related to water temperature because a substantial water temperature difference (degree days of 1761 and 2563) occurred between study reaches. In sympatry, H. pacifica adults began emerging 2 weeks earlier than C. sabulosa, when water temperature reached 9°C. The emergence of H. pacifica was synchronous and male biased. The emergence of C. sabulosa was protandrous and male biased and began when water temperature reached 17°C. Claassenia sabulosa emergence was extended and lasted for 6 weeks during July and August. The abundance of C. sabulosa adults during this period corresponded closely to fluctuations in water temperature."
The United States Geological Survey (USGS) National Water Quality Assessment Data Warehouse (NAWQA) shows this species is present in Gunnison County. Data as of 1Sep2005
Ward,JV, Kondratieff,BC and Zuellig,RE 2002 An Illustrated Guide to the Mountain Stream Insects of Colorado. 2nd ed. University Press of Colorado, Boulder, Colorado. 219 pages.
Illustration of Hesperoperla pacifica nymph on page 66.
Ziegler,DD and Stewart,KW 1977 Drumming behavior of eleven Nearctic stonefly (Plecoptera) species
Annals of the Entomological Society of America. 70(4)495-505.
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