A two-year emergence trap study of black flies at four sites in northwestern Pennsylvania yielded 1%3 individuals of nine species. The collections included Prosimulium mixtum, P. jU5cum, Stegapterna mutata, Simulium aureum, S. excisum (recorded for the first time from Pennsylvania), S. gauldingi, S. sp. nr. innacens, S. vittatum, and S. tuberasum. Species richness for all sites peaked during May. Emergence collections below a sewage plant effluent outfall represented fewer individuals and species than collections above the effluent outfall. Chromosomal analysis of supplementary larval collections revealed the IIIL-l and IS-7 sibling species of S. vittatum and the FG sibling of S. tuberasum

Adler, P. H

Kim, K. C

Masteller, E. C

Travis, B. L

English

ValpoScholar

Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae) in Northwestern Pennsylvania

Valparaiso University

The Great Lakes Entomologist Volume 15 Number 4 - Winter 1982 Number 4 - Winter 1982 Article 5 December 1982 Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae) in Northwestern Pennsylvania P. H. Adler Pennsylvania State University B. L. Travis Pennsylvania State University K. C. Kim Pennsylvania State University E. C. Masteller Pennsylvania State University Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Adler, P. H.; Travis, B. L.; Kim, K. C.; and Masteller, E. C. 1982. "Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae) in Northwestern Pennsylvania," The Great Lakes Entomologist, vol 15 (4) Available at: https://scholar.valpo.edu/tgle/vol15/iss4/5 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. 1982 THE GREAT LAKES ENTOMOLOGIST 253 SEASONAL EMERGENCE PATTERNS OF BLACK FLIES (DIPTERA: SIMULIIDAE) IN NORTHWESTERN PENNSYLVANIAi P. H. Adler,2 B. L. Travis,3 K. C. Kim,2 and E. C. Masteller3 ABSTRACT A two-year emergence trap study of black flies at four sites in northwestern Pennsylvania yielded 1%3 individuals of nine species. The collections included Pro imuli m mixtum, P. jU5cum, Stegapterna mutata, Simulium aureum, S. excisum (recorded for the first time from Pennsylvania), S. gau/dingi, S. sp. nr. innacens, S. vittatum, and S. tuberasum. Species richness for all sites peaked during May. Emergence collections below a sewage plant effluent outfall represented fewer individuals and species than collections above the effluent outfall. Chromosomal analysis of supplementary larval collections revealed the IIIL-l and IS-7 sibling species of S. vittatum and the FG sibling of S. tuberasum. The immature stages of black flies are a near-ubiquitous component of Pennsylvania rivers and streams. In certain areas of the state the adult stage of some species often attains pest status. However, only four papers have dealt directly with the black flies in Pennsyl­vania (Frost 1949, Goulding and Deonier 1950, Stone and Iamnback 1955, Eckhart and Snetsinger 1%9). Accordingly, faunal and biological studies of black flies in the state are far from complete. The present study was, therefore, undertaken to determine the species composition and emergence patterns of adult black flies in northwestern Pennsylvania. MATERIALS AND METHODS Four sites in Erie County, Pennsylvania, were used for collections of emerging aquatic insects (Fig. I). The Sixmile Creek site (42°7' 10" N,79°57' 15" W) at an elevation f 344 m had a substrate with phi values of 42% retained by -5</> (coarse rubble) and 32% between -4d> and Od> (medium to fine pebbles) (method of determination in Masteller 1980). Fourmile Creek (42'9'35" ~. 80° I'50" W), with two collection sites, had a phi classification of 37% retained by -5d> and 399<: between -4</> and O</>. Site I at an elevation of 287 m was 460 m above a 51.000 gallon per day extended aeration sewage plant effluent outfall. Site 2 at an elevation of 256 m was 90 m below the sewage effluent outfall. Sixmile and Fourmile Creek flow into Lake Erie. Conneauttee Creek (41°51'26" N, 80°2'22" W) is a tributary of Big Conneauttee Creek which flows into French Creek, subsequently into the Allegheny River, and eventually into the Ohio River. This site at an elevation of 443 m had phi categories of 579'c retained by -5</> and 219'c between -4</> and O</>. Two trap designs were used. The emergence trap on Sixmile Creek was constructed from Lumite' special screen. a type of shadecloth used in pollination (design in Masteller [1977] and ~fasteller and Flint [1980a]). Each trap on the remaining sites was a flare parachute (mesh size 0.0025 mm) obtained as surplus from the U.S. Marine Corps. IAuthorized for publication on 18 May 1982 as Paper No. 6441 in the Journal Series of the Pennsylvania Agricultural Experiment Station, University Park, PA 16802. contribution from The Frost Entomologi· cal .\Iuseum. The Pennsyhania State University (AES Proj. No. 2328). ~The Frost Entomological Museum, Department of Entomology, The Pennsylvania State University, Uni\ersity Park. PA 1680~. 3Division of :>;atural Sciences and Engineering, Behrend College, T e Pennsylvania State University, Erie. PA 16563. 1Adler et al.: Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae)Published by ValpoScholar, 1982254 THE GREAT LAKES ENTOMOLOGIST Vol. 15, No.4 All streams were spring fed, first order streams that flowed through climax forests domi­nated by beech (Fagus grandijolia), maple (Acer spp.), and hemlock (Tsuga canadensis). Emergence of aquatic insects has been studied on Sixmile Creek since 1977, at site I on Fourmile Creek since 1980, at site 2 only in 1981. and on Conneauttee Creek since 1980. Insects were collected from the traps on a regular sequence with mechanical aspimtors. Collections were made in the afternoon on alternate days during heavy emergence, and were placed at -5°C before transfer to 70% ethanol for sorting and identification. Water tempera­tures were recorded at the time collections were made. Conductivity readings were recorded during 1981 with a YSI 33 meter. Weekly analyses of ammonia (as N) were performed by Church Laboratories, Erie, Pennsylvania, on water samples collected from the sewage effluent 90 m above site 2 n Fourmile Creek. Larval collections from directly below each tmp site were preserved in Carnoy's fixative during June 1979, 1981, and early 1982 for all sites except Conneauttee Creek. A voucher collection of adults and larval chromosomes is located in The Frost Entomological Museum of The Pennsylvania State University. RESULTS AND DISCUSSION A combined total of 1963 adult black flies of nine species were collected from the four trap sites over a two year period. The species and their totals (males:females) were: Prosimulium fuscum Syme and Davies (4:29), P. mixtum Syme and Davies (12:94), Stegopterna mutata (Malloch) (2:418), Simulium IEusimulium) aureum Fries (3:30), S. IE.) excisum Davies, Peterson, and Wood (3:0), S. (E.) gaulding! Stone (59:35), S. (E.) sp. nr. innacens (Shewell) (0:2), S. (Psi/azia) vittatum Zetterstedt (130:243), and S. (S.) tuberosum (Lundstrom) (372: 526). The present collection includes the first record of S. excisum in Pennsylvania and raises the state species t tal ( ncluding sibling speci s) to 33. Specimens identified as Simulium species nr. illllocells may, in fact, be S. excisum. Females of many S. (Eusimulium) species are virtually impossible to identify with any certainty. Females predominated at each site for 8000' t BOUNDARY LINES STATEN COUNTY SCALE _ 42'00 Fig. I. Map of northwestern Pennsylvania detailing the collection sites: a = Fourmile Creek. sire two; b = Fourmile Creek. site one; c Sixmile Creek; d = Conneauttee Creek. 2The Great Lakes Entomologist, Vol. 15, No. 4 [1982], Art. 5https://scholar.valpo.edu/tgle/vol15/iss4/51982 THE GREAT LAKES ENTOMOLOGIST 255 all species except the ornithophilic S. gouldi lgi and S. excisum, although only three speci­mens of the latter were collected. The low numbers of male St. mutata collected in this study (two from Sixmile Creek) are indicative of predominantly parthenogenetic triploid popula­tions (Basrur and Rothfels J959). Emergence periods of black flies and maximum-minimum water temperatures are shown for the four trap sites (Figs. 2-5). Week numbers given in Figures 2-7 follow the system of Taylor and French (1972) as reported in Masteller and Flint (I980b) where week number I corresponds to January I-January 7. Site 1 on Fourmile Creek (average conductivity 303.4 fLmhos/cm, range = 170-420 fLmhos/cm, Fig. 2) and Sixmile Creek (average conduc­tivity 221.1 fLmhos/cm, range 80-420 fLmhos/cm, Fig. 3) were very similar in species composition with a peak for species richness in May. However, the polyvoltine species (S. aureum, S. vittatum, and S. tuberosum) at site 1 on Fourmile Creek emerged in large numbers into October and November of both years. Emergence of S. vittatum (Fig. 6) and S. tuberosum (Fig. 7) at site 1 on Fourmile Creek typically indicated three to four population peaks annually. The polyvoltine species at Sixmile Creek showed a shortened emergence with only nine individuals (all S. tuberosum) emerging later than mid-July in 1981. Reasons for a depauper­ate black fly fauna at Sixmile Creek in 1980 (seven individuals collected) are unknown, fusc";"~" ProsmJIi.m mixtum !·;:rta~·K Simulium aureum Simulium exc;sum Simulium gouldingi Simulium vi!tatum Simulium tuberosum 20 15 10 5 U 0 0 °",20 ::r: 15 10 5 CJ-FOURMILE CREEK SITE 1 CI c::::J 1980-1981 I I-I I : I : I I I --I I I I : : : I I I I I' I' I I. IIII III I I III d II I I I III , 1980 11"i,,111, "i,III,II'11 11'11 I 1981 0 16 20 24 28 32 36 40 44 WEEK Fig. 2. Emergence periods f black flies with respect to water temperature at site I on Fourmile Creek. Erie County. PA during !980-1981. Heavy vertical marks on the emergence bars indicate 5O'k emer­gence: light vertical marks indicate 25S7c and 75'7< emergence. respectively. 3Adler et al.: Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae)Published by ValpoScholar, 1982256 THE GREAT LAKES ENTOMOLOGIST Vol. 15, No.4 ProsimuJium fuscum Prosimulium mixtum Stegoptema mutata Simulium aureum Simulium excisum Simulium vittatum Simulium tuberosum 20 15 10 5 ..u 0 0('120 :z: 15 10 5 0 c -SIX MILE CREEK C----'TI I r::::::::J 1980-1981 IIIII I I ' I I I II I III I I 1980 I I I I I I I I I I I III I I I III' I I I' I ,II II I 1981 II 'II I I I I 12 16 20 24 28 32 36 40 WEEK Fig. 3. Emergence periods of black flies with respect to water temperature at Sixmile Creek, Erie County, PA during 19SG-19S!. although concomitant collections of Trichoptera and Plecoptera were also lower than usual. Sixmile Creek warm d more rapidly and subsequently maintained a higher temperature during 1980 and 1981 than did all other sites. The early warming was probably responsible for earlier emergences of the Prosimulium spp. Site 2 on Fourmile Creek (average conductivity = 289.2 /Lmhos/cm, range 130-480 /Lmhos/cm, Fig, 4) was poorer in individual and species numbers in 1981, presumably because of its location below a sewage treatment facility, Levels of ammonia at the effluent outfall 90 m above this site sometimes exceeded 30.0 mg/litre while coliform counts reached 40,000 per 100 m!. However, ammonia and coliform levels at the actual trap site were undoubtedly lower, partiCUlarly in spring when the water level was higher. Ammonia con­centrations of 0.6 mg/litre can cause IOOCk mortality among laboratory-reared black fly larvae (Grunewald 1972). From mid-June to September, the ammonia concentration at the effluent outfall averaged 1.0 mg/litre, during which time 82.3% of the black flies at site 2 emerged. Back and Harper (1979) divided black flies into two groups, based on emergence studies in the Laurentides of Quebec: (I) a univoltine group that begins to emerge in mid-May and includes the Prosimulium spp. and SI. mulala, and (2) a polyvoltine group that begins to emerge the third week of May (earlier for S. ~itlalum) and includes S. aureum, S. vitlalum, and S. tuberosum. These groupings are applicable to data of the present study which were 4The Great Lakes Entomologist, Vol. 15, No. 4 [1982], Art. 5https://scholar.valpo.edu/tgle/vol15/iss4/51982 THE GREAT LAKES ENTOMOLOGIST 257 == Stegopterna mutata FOURMILE CREEK Simulium aureum SITE 2 1981 S. tuberosum~S. vittatum 14 20 I II I II I I' I(J 15 I · I I I " 0 N Z 10 1/1 I"' I I • " 5 0 14 18 22 26 30 34 38 WEEK ... 	Emergence patterns of black flies with respect to water temper u e at site 2 on Fourmile Creek. Coumy. PA during 1981. Ammonia was measured at a sewage outfall 90 m above the site. collected 4° farther south and about 5° farther west. However, emergence of the univoltine group plus S. vittatum began over a month earlier than in the Laurentides and i  Davies' (1950) ten-ycar study in Algonquin Park, Ontario. A decrease in latitude, therefore, tends to generate a longer flight period, particularly for the polyvoltine species. Water temperature is a major determinant of such trends since it influences egg hatching and larval development rates (Ross and Merritt 1978). Inception of emergence in the present study occurred shortly aftcr water temperatures reached lO°e. Fall emergence of S. vittatum and S. tuberosum also terminated when water temperatures con­sistently registcred below lOoC (Fig. 2). The latest emergence dates for these species in the Laurentides and in Algonquin Park were at least six weeks earlier. Members of the univol­tine group at alI four trap sites completed their emcrgence before maximum water tempera­tures consistently exceeded 15°C. Only species of the univoltine group, with the exception of one female S. tuberosum. were collected from Conneauttee Creek (Fig. 5) which ceased to flow in mid-july 1980 and early June 1981. St. mlltata was the most abundant species (395 individuals) at this site in both years. S. gouldingi was second in abundance (91 individuals) during 1980. but exhibited a very restricted period of emergence. In 1981 only three males ofS. gouldingi emerged before the flow terminated. Although S. gouldingi is reported to be univoltine (Stone and lamnback 1955, Davies et al. 1962) we have found adults into late September in central Pennsylvania. Species of the polyvoltine group such as S. vittatum may be precluded from colonizing intermittent streams, in part, because their eggs are unable to withstand dessication (Wu 1931). However, polyvoltine species are good colonizers of stream areas such as site 2 on Fourmile Creek that are alternately polluted and unpolluted over time. S. aureum, S. vittatum, and S. tuberosum are actually species complexes of. respectively, 10 (K. H. Rothfels, pers. comm.), two (Rothfels 1981), and nine (Mason 1982) morphologi­5Adler et al.: Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae)Published by ValpoScholar, 1982258 THE GREAT LAKES ENTOMOLOGIST Vol. 15, No.4 Prosimulium fuscum Prosimulium mixtum Stegopterna mutata Simulium excisum Simulium sp nr. innocens i li  gouldingi Simulium tuberosum 15 10 ~ 5 o 0:r 15 10 5 o CONNEAUTTEE CREEK c:::::::I1980 -1981 c::::J-I 1:1 :: ' I I I II: :: , -C t::::r--f-i­i-I I II I I II I I 1980 i­i­f-I III I I I I 1981 I I 14 18 22 26 WEEK Fig. 5. Emergence periods of black flies with respect to water temperature at Conneauttee Creek, Erie County. PA during 1980-1981. cally inseparable species (sibling species). The IS-7 sibling of S. vittatum was collected as larvae in mid-J une 1981 and IO April 1982 from Fourmile Creek (site I) and the IIIL-I sibling was collected in mid-June 1981 from Sixmile Creek. Both the IIIL-I and IS-7 siblings were collected from Fourmile Creek (site l) throughout June 1979. Larvae of the FG sibling of S. tuberosum were collected in mid-June 1981 from Fourmile Creek (sites I and 2) and Sixmile Creek. Larvae of S. aur um were not examined. Due to the presence of more than one sibling species, emergence patterns and number of generations for some species should be interpreted cautiously. 6The Great Lakes Entomologist, Vol. 15, No. 4 [1982], Art. 5https://scholar.valpo.edu/tgle/vol15/iss4/51982 THE GREAT LAKES ENTOMOLOGIST 259 FOURMILE CREEK SITE 1 1980 Simulium vittatum Fig. 6. Emergence patterns for males and femaJes of Simulium Villatllm at Site 1 on Fourmile Creek. Erie County. PA during 1980. FOURMILE CREEK SITE 1 1981 Simuliu!11 tuberosum Fig. 7. Emergence for males and females of Simlllillm wbervslIm at Site 1 on Fourmile Creek. Erie County. 1981. 7Adler et al.: Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae)Published by ValpoScholar, 1982260 THE GREAT LAKES ENTOMOLOGIST Vol. 15, No.4 ACKNOWLEDGMENTS We thank Dr. B. V. Peterson, Biosystematics Research Institute, Agriculture Canada, for identifications and verifications of certain specimens; Dr. K. H. Rothfels and Dr. G. F.Mason of the University of Toronto for cytotyping the 1979 larval collections of S. vittatum and all larval collections of S. tuberosum, respectively; and C. Yencho for generous assis­tance with the collecting and sorting of specimens. Dr. C. W. Pitts, C. R. Loerch, and Dr. D. J. Shetlar kindly reviewed the manuscript. LITERATURE CITED Back, C. and P. P. Harper. 1979. Succession saisonniere, emergence, voltinisme et repartition de mouches noires des Laurentides (Diptera; Simuliidae). Canadian J. Zoot. 57:627-{)39. Basrur, V. R. and K. H. Rothfels. 1959. Triploidy in natural popUlations of the black fly Cnephia mutata (Malloch). Canadian J. Zoo!. 37:571-589. Davies, D. M. 1950. A study of the black fly population of a stream in Algonquin Park, Ontario. Trans. Royal Canadian Inst. 28:121-159. Davies, . M., B. V. Peterson and D. M. Wood. 1962. The black flies (Diptera: Simuliidae) of Ontario. Part I. Adult identi!ication and distribution with descriptions of six new species. Proc. Entomol. Soc. Ontario 92:70-154. Eckhart, P. and R. Snetsinger. 1969. Black flies (Diptera: Simuliidae) of northeastern Pennsylvania. Melsheimer Entomol. Ser. 4: 1-7Frost, S. W. 1949. The Simuliidae of Pennsylvania (Dipt.). EntomoL News 60: 129-131. Goulding, R. L. and C. C. Deonier. 1950. Observations on the control and ecology of black flies in Pennsylvania. J. Econ. Entomol. 43:702-704. Grunewald, J. 1972. Die Bedeutung der Stickstoff-Exkretion und Ammoniak-Empfindlich­keit von Simuliiden-Larven (Diptera) fur den Aufau von Laboratoriumskulturen. Z. Angew. Entomo!. 85:52-60. Mason, G. F. 1982. Cytological studies of sibling species of S mulium tuberoswn (Lundstrom) (Diptera: Simuliidae). Canadian J. Zoo!. 60:292-303. Masteller, E. C. 1977. An aquatic emergence trap on a shale stream of western Pennsyl­vania. Melsheimer Entomol. Ser. 23: 10-15. ----. 1980. The impact of oil drilling operations on aquatic insects. U.S. Environmental Protection Agency, Report No. EPA-68-03-2647, p. 1-63. Masteller, E. C. and O. S. Flint. 1980a. Emergence phenology of TricllOptera from Six Mile Creek, Erie County, Pennsylvania, U.S.A. Aquatic Insects 2:197-210. ----. 1980b. Caddisfly (Trichoptera) emergence patterns from two streams ofthe Alle­gheny National Forest area of Pennsylvania. Melsheimer Entomo!. Ser. 29: 12-22. Ross, D. H. and R. W. Merritt. 1978. The larval instars and popUlation dynamics of five species of black flies (Diptera: Simuliidae) and their responses to selected environmental factors. Canadian J. Zoo!. 56: 1633-1642. Rothfels, K. H. 1981. Cytological approaches to the study of black fly systematics and evolution. p. 67-83 in M. W. Stock (ed.). Application of genetics and cytology in insect systematics and evolution. Proc. Symp. Natl. Meeting EntomoL Soc. Amer. Atlanta, Dec. 1-2, 1980. Stone, A. and H. A. Jamnback. 1955. The black flies of New York State (Diptera: Simuliidae), Bull. New York State Mus. 349:1-144. Taylor, L. R. and R. A. French. 1972. Rothamsted Insect Survey. Rep. Rothamsted Exp. Sta. for 1972 Pt. 2, p. 182-211. Wu, Y. F. 1931. A contribution to the biology of Simulium (Diptera). Michigan Acad. Sci., Arts and Letters 13:543-599. 8The Great Lakes Entomologist, Vol. 15, No. 4 [1982], Art. 5https://scholar.valpo.edu/tgle/vol15/iss4/5

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Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae) in Northwestern Pennsylvania

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