The Distribution and Life History of Axymyia Furcata Mcatee (Diptera: Axymyiidae), a Wood Inhabiting, Semi-Aquatic Fly Matthew .W Wihlm Iowa State University

Entomology Publications Entomology

2011 The Distribution and Life History of Axymyia furcata McAtee (Diptera: Axymyiidae), a Wood Inhabiting, Semi-Aquatic Fly Matthew .W Wihlm Iowa State University

Gregory W. Courtney Iowa State University, [email protected]

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Abstract Axymyia furcata McAtee (Diptera: Axymyiidae) is a xylophilic, semiaquatic fly from eastern North America. As part of a comprehensive study of the fly's distribution, life history, and phylogeography, we surveyed populations of A. furcata in the eastern United States and Canada. Collecting and rearing methods are described, and use of the niche modeling software, DIVA GIS, to locate regions with potentially suitable habitat is presented. Based on historical records and our recent survey, A. furcata is confirmed to occur from southern Ontario and Quebec, across the northern tier of states from Minnesota to Maine, and south along the Appalachian Mountains to Georgia and South Carolina. Our survey resulted in several new state records and demonstrated that A. furcata, a fly once considered quite rare, can be abundant (> 200 individuals in a single log) in suitable habitats. Larvae and pupae are most abundant in wet and partially submerged logs in small streams and seeps. Axymyia furcata has four larval instars, overwinters as larvae, and has adults that emerge primarily in March and April in the southern Appalachians and somewhat later (e.g., to late May) in the northern Appalachians, upper Midwest, and southern Canada.

Keywords habitat, xylophagy, rearing, larval instars, phenology, ecological niche modelling

Disciplines Behavior and Ethology | Ecology and Evolutionary Biology | Entomology | Population Biology | Terrestrial and Aquatic Ecology

Comments This article is published as Wihlm, Matthew W., and Gregory W. Courtney. "The distribution and life history of Axymyia furcata McAtee (Diptera: Axymyiidae), a wood inhabiting, semi-aquatic fly." Proceedings of the Entomological Society of Washington 113, no. 3 (2011): 385-399.. doi: 10.4289/0013-8797.113.3.385. Posted with permission.

This article is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/ent_pubs/499

The Distribution and Life History of Axymyia furcata McAtee (Diptera: Axymyiidae), a Wood Inhabiting, Semi- Aquatic Fly Authors: Matthew W. Wihlm, and Gregory W. Courtney Source: Proceedings of the Entomological Society of Washington, 113(3) : 385-398 Published By: Entomological Society of Washington URL: https://doi.org/10.4289/0013-8797.113.3.385

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THE DISTRIBUTION AND LIFE HISTORY OF AXYMYIA FURCATA MCATEE (DIPTERA: AXYMYIIDAE), A WOOD INHABITING, SEMI-AQUATIC FLY

MATTHEW W. WIHLM AND GREGORY W. COURTNEY

(MWW, GWC) Department of Entomology, Iowa State University, 3222 Science II Bldg., Ames, Iowa 50011-3222 (e-mail: [email protected]); (MWW) Current address: Pioneer Hi-Bred International, Inc., 7250 NW 62nd Ave., Johnston, Iowa 50131-0552

Abstract.—Axymyia furcata McAtee (Diptera: Axymyiidae) is a xylophilic, semi- aquatic fly from eastern North America. As part of a comprehensive study of the fly’s distribution, life history, and phylogeography, we surveyed populations of A. furcata in the eastern United States and Canada. Collecting and rearing methods are described, and use of the niche modeling software, DIVA GIS, to locate regions with potentially suitable habitat is presented. Based on historical records and our recent survey, A. furcata is confirmed to occur from southern Ontario and Quebec, across the northern tier of states from Minnesota to Maine, and south along the Appalachian Mountains to Georgia and South Carolina. Our survey resulted in several new state records and demonstrated that A. furcata, a fly once considered quite rare, can be abundant ([ 200 individuals in a single log) in suitable habitats. Larvae and pupae are most abundant in wet and partially submerged logs in small streams and seeps. Axymyia furcata has four larval instars, overwinters as larvae, and has adults that emerge primarily in March and April in the southern Appalachians and somewhat later (e.g., to late May) in the northern Appalachians, upper Midwest, and southern Canada. Key Words: habitat, xylophagy, rearing, larval instars, phenology, ecological niche modelling DOI: 10.4289.0013-8797.113.3.385

The Axymyiidae are an enigmatic Bertone et al. 2008). The family includes group of semi-aquatic nematocerous flies, three extant genera, Axymyia McAtee, considered to be the most ancestral family Mesaxymyia Mamayev, and Protaxymyia in the infraorder Bibionomorpha in some Mamayev and Krivosheina (Mamayev classifications (Oosterbroek and Courtney 1968), containing seven described spe- 1995) but whose placement is uncertain cies. Of the described species, all but one in others (e.g., Wood and Borkent 1989, occur in the Palearctic Region, where they are found in Hungary and Russia (Mamayev 1968), China (Yang 1993), * Edited by Martin Hauser; accepted by Robert R. Taiwan (Papp 2007), and Japan (Hiroshi Kula 1953). Nearctic axymyiids include one

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described species in the east, Axymyia holotype; University of Guelph Insect furcata McAtee (McAtee 1921), and a Collection, Guelph, ON (UGIC); Uni- single undescribed species in Oregon versity of Minnesota Insect Collection, (Wood 1981). Prior to 2005, A. furcata St. Paul, MN (UMIC); and University of hadbeenreportedfromtwoCanadian Wisconsin Insect Research Collection, provinces and 10 U.S. states but was Madison, WI (UWIC). We also consulted considered rare throughout its range. In original descriptions of adults (McAtee addition, three extinct genera, Sinaxymyia 1921) and larvae (Krogstad 1959) of A. Zhang, Juraxymyia Zhang, and Psocites furcata as well as more recent accounts of Hong, are known from Kazakhstan and the family (e.g., Wood 1981, Krivosheina China (Zhang 2010). 2000) and available keys to the North Published information on the ecology American fauna (e.g., Courtney and of axymyiid flies has been limited. Early Merritt 2008). records (e.g., Krogstad 1959) indicated Ecological niche modeling.—The eco- that larvae reside inside self-dug chambers logical niche modeling program DIVA- within saturated, decomposing woody de- GIS 5.2 (Hijmans et al. 2005) was used bris. After two years, the larvae pupate as a secondary tool to identify potential inside the same logs and emerge as adults A. furcata populations. DIVA-GIS works in early to mid-spring (Krogstad 1959, by running GPS coordinates against 19 Wood 1981). Adults possess vestigial bioclimatic variables based on temper- mouthparts and are thought to be short- ature and precipitation in the BIOCLIM lived (Wood 1981). Published informa- algorithm. The program uses the results tion on most aspects of A. furcata life to construct a map that estimates the history (e.g., oviposition, overwintering distribution of A. furcata and applies stage, phenology) and general biology a basic color gradient to project the level (e.g., adult behavior, “host” log prefer- of probability of A. furcata being present ence) are lacking. within that distribution. The GPS coor- The objectives of our research in- dinates used to create the map originated from prior collecting by our lab, as well cluded a detailed study of axymyiid life as points based on literature and speci- history and an intensive survey of these men labels from various university and flies in eastern North America, partly to museum research collections. Existing test if axymyiids are indeed rare or merely records included adult females collected under-collected. in Pennsylvania and Virginia (McAtee 1921) and various life stages from Mas- MATERIALS AND METHODS sachusetts (Alexander 1942), Minnesota Comparative material.—Specimens (Krogstad 1959), Ohio (Peterson 1960), collected during this study were com- New York (McAtee 1921), North Carolina pared with material from several re- (Wood 1981), and Wisconsin (Young and search collections: Canadian National Lisberg 2001) in the United States, and Collection of Insects, Arachnids, and Ontario and Quebec in Canada (Wood Nematodes, Ottawa, ON (CNC); Cornell 1981). Unpublished records from Mary- University Insect Collection, Ithaca, NY land and New Jersey were obtained from (CUIC); Museum of Comparative Zool- pinned material in the USNM. On com- ogy, Cambridge, MA (MCZ); United pletion of the DIVA-GIS analysis, we then States National Museum of Natural His- used state atlases, park descriptions, and tory, Washington, DC (USNM), including past publications to ﬁnd possible collecting

sites within areas DIVA-GIS mapped as Collection, Ames, IA (ISIC), USNM, having reasonable probability of finding and CNC. axymyiids. Rearing methods.—Because of the Collection methods.—Once a seem- short adult life and the paucity of pinned ingly suitable habitat was located, any adult material in university and mu- saturated and somewhat decomposing seum research collections, the rearing of woody debris was checked for axymyiid larvae and pupae was critical to evalu- larvae or pupae. An effective initial check ating characteristics of adult A. furcata. is to balance the log between two rocks An effective rearing method involved or logs and apply pressure to the log the placement of field-collected pupae with the heel. When A. furcata is pres- in individual wells of a 24-well cell- ent, the log typically breaks where lar- culture cluster plate (or standard Petri val galleries have weakened the wood, dish), with each specimen placed either thereby exposing resident larvae or pu- between layers of damp paper towel or pae. For careful and thorough removal of in moss or soft, finely-crumbled wood. all larvae and pupae, each inhabited log Alternatively, especially when enumer- can then be dissected with a knife or ation of all individuals or rearing of screwdriver. In our study, we often also all adults from a log were objectives, we scanned the resulting woody detritus collected intact pieces of colonized logs under a dissecting microscope, which for transport back to the laboratory. All was especially helpful in finding early such logs were gathered just prior to instars. When pupae were present, they adult emergence (determined by sam- were either preserved in 95% EtOH or ples from adjacent logs), maintained in placed in a vial or dish containing damp either loosely sealed plastic tubs or plas- paper towel, moss, or small pieces of damp tic bags, and checked daily for emerged wood, where specimens could be held for adults and misting with water (to ensure adult rearing (see below). Emergence and the log remained moist). In most cases, the Malaise traps were also used to collect log was kept cool during transport back to adult A. furcata. Traps usually were placed the lab and then placed in an incubator set in the flyway over a seep or small stream, tomimictheapproximatehighandlow usually near woody debris suspected of temperatures of the original habitat at the harboring axymyiids. All field-sampled, time of collection. However, we also laboratory harvested, and reared speci- maintained several logs on a laboratory mens were collected into 70% or 95% bench at ambient room temperature. ethanol for further examination. Various Larval-instar determination.—Two sites were searched throughout the year measurements were recorded from the for the presence of A. furcata.Theas- dorsal surface of the head capsule: sumed two-year larval stage was apparent (1) across the widest point and (2) at at most sites, as evidenced by the presence the anterior margin of the head capsule, of either of two size classes of larvae or just posterior to the base of the man- mid-stage larvae and pupae. Assuming dibles. Both measurements were taken a two-year life cycle is typical of most from the more heavily sclerotized regions populations, we considered any “negative” of the head because they show less vari- collections as evidence that A. furcata ation within each instar and provide was absent from that location. Speci- better separation between instars. This is mens collected during this study have unlike overall body length, where sub- been deposited in the Iowa State Insect stantial overlap occurs between instars.

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RESULTS AND DISCUSSION not generally support populations of this Distribution.—A DIVA-GIS analysis species. That said we occasionally found identified several potentially suitable colonized logs above the water level of larger streams, but usually in a floodplain areas for A. furcata and formed the par- where evidence of recent scouring of tial basis for subsequent searches in tributary streams was apparent. eastern North America. After extensive The characteristics of the riparian zone collection throughout the eastern United appear to be important in the distribution States, the first records of the family can of A. furcata. Our records indicate that be confirmed in 10 states: Connecticut, areas with this species are well forested, Georgia, Iowa, Kentucky, Maine, New consisting of a hardwood or a mixed Hampshire, Tennessee, South Carolina, canopy, with trees close enough to the Vermont, and West Virginia. A summary aquatic habitat to provide limbs or other of recent collecting records in the east- coarse woody debris for potential larval ern U.S. is presented in Appendix 1. colonization. Most hardwood forests at Although our records fill significant gaps known A. furcata sites consist primarily in the known distribution of these flies, of maple, beech, birch, aspen, and oak. In we predict that additional collecting in some of the fly’s range, habitats also had the eastern United States and Canada smaller amounts of hemlock, white pine, will expand the known range of A. fur- or rhododendron incorporated into the cata. A DIVA-GIS analysis that in- hardwood stand. Our data confirm that corporated all records from the current A. furcata larvae occur primarily in elm study provided the same prediction. (Peterson 1960), maple (Alexander 1920), Habitat and larval behavior.—Ax- aspen (Krogstad 1959), and hickory ymyia furcata occurs in a variety of (genus Carya), and rarely in rhododen- aquatic environments. Although first dron. Axymyia furcata varies signifi- identified from damp logs in a “swampy cantly from the axymyiid (Protaxymyia woodland” (Krogstad 1959), our study sp.) reported from Oregon, which resides indicates that A. furcata occurs primarily primarily in softwoods (i.e., conifers). in small, lotic habitats, including seeps, Although the western species was springs, and streams (Figs. 1a–e). The first recorded from alder (Dudley and lentic habitat (swampy woodland) origi- Anderson 1982), the larvae appear to be nally described by Krogstad (1959) ap- most common in cedar (S. Fitzgerald pears to be unique to that population pers. comm.) or Douglas fir (G. Courtney in northern Minnesota. Furthermore, we unpbl.). found that A. furcata does not generally Krogstad (1959) was the first to de- occur in intermittent or torrential habitats scribe the wood in which A. furcata or in areas prone to frequent and rapid larvae reside. He noted that the wood flooding. Because the larval stage must must be in the beginning stages of de- survive throughout the year (see below) composition, free of moss and bark, wet and requires a continuously moist habitat enough to yield water when a knife blade (Wood 1981, M. Wihlm and G. Courtney is inserted, and soft enough to push a unpbl.), intermittent water bodies do not pencil into it. Wood (1981) also noted appear to support these flies. Likewise, that the wood, though rotting, should be larval habitats must remain in the stream light in color and firm enough that pry- or seep for extended periods, so large, ing it apart is difficult. During our in- torrential, and/or flood-prone systems do vestigations we found these criteria to

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be mostly true; however, we often found Early descriptions of the larval cham- larvae in logs covered by moss or with bers of Axymyiidae suggested that the bark remnants (see Fig. 1f). Level of de- chambers are usually short (3–6 cm) composition varied from that similar to and primarily straight (Krogstad 1959, the description by Krogstad (1959) to Mamayev and Krivosheyna 1966). Wood wood that was so fresh it was difficult (1981) reported further that each larva to insert a knife or flat head screwdriver. occurs in an individual gallery, with each Our larval samples have come from wood gallery an oval tunnel that gradually in- ranging from small branches (3–5 cm creases in diameter as the larva grows diameter) to larger tree trunks (> 20 cm and burrows deeper toward the center of diameter). the wood. Although some variation is ap- Although we have not tested the re- parent across geographical areas and pop- lationship between microhabitat suit- ulation densities, we frequently observed ability and log position, we suspect a more complex galleries resulting from correlation. We have sampled logs from multiple larvae residing in the same cross a variety of locations, and the position of section of a log (Fig. 1f). Regardless, the the log seems to influence the pattern of original opening of the gallery is quite colonization by A. furcata larvae. Wood small and formed when the first instar lying horizontally on a cool, damp sub- burrows into the log after hatching from stratum or in a few centimeters of water the egg. was often colonized only in the wettest Once the gallery is created, the larva strip along the ventrolateral section of often resides in a distinctive position, the log. Wood lying in deeper pools (i.e., with the distal tip of the anal respiratory mostly submerged) was usually inhabited siphon at the outside opening of the log only across the top of the log down to the (Fig. 1i). Krogstad (1959) suggested that water surface but rarely below the sur- the larva uses its siphon to remain sus- face. When logs were leaning from the pended in the chamber, a behavior thought bank into the water, larvae were concen- possible with the aid of the spinelike trated in a saturated band just above the structures at the apex of the siphon water surface where water had wicked (Krivosheina 2000; see figs. 4.177–178 up the wood. In some cases we found in Courtney et al. 2000). However, we colonized logs just above the water, found little evidence that larvae remain supported by rocks or other woody de- in such a position for long periods. The bris, and where water splashed onto the larval siphon is quite elastic, stretching underside of the log. In such logs A. and contracting as the larva moves furcata larvae inhabited the saturated within the chamber (Krivosheina 2000, bottom and lower sides kept wet from the W. Wihlm and G. Courtney pers. obs.). splashing. Axymyia furcata was reported to spend

Fig. 1. Axymyia furcata habitat and immatures at wood surface. a, Roaring Brook, Franklin Co, MA; b, Macedonia Brook, Litchﬁeld Co., CT; c, Tributary of Big Pine Creek, Hocking Co., OH; d, Log Road Hollow, Clinton Co., PA; e, Tributary of Palmer Creek, Haywood Co., NC; f, Larval galleries, Coweeta Hydrological Laboratory, Macon Co., NC; g, Pupa, anterior portion of thorax and respiratory organs, in situ, seep near Rough Fork, Haywood Co., NC; h, Larval galleries, Coweeta Hydrological Laboratory, Macon Co., NC; i, Larva, apex of respiratory siphon, in situ, seep near Rough Fork, Haywood Co., NC. Arrows on Figs. a–e indicate logs colonized by Axymyia.

most of its larval stage with the head Palearctic axymyiids are known to capsule pointed toward the distal end of push debris out of the gallery and onto the chamber (i.e., away from wood the outside surface of the log. This forms surface) and turning back toward the small piles of wood particles that are opening just prior to pupation (see ﬁg. 2 easily recognizable as evidence of axy- in Krogstad 1959). However, we have myiid activity (Krivosheina 2000). This observed larvae of nearly all instars (II– behavior was occasionally observed in IV) in this position (Fig. 3b), as well A. furcata, but more often we noted as a variety of other positions, and lar- a moist, pasty mixture of minute wood vae appear to move easily throughout particles and frass within the gallery. As their chambers. Prior to pupation larvae the larva burrows farther into the log, will reposition themselves as aforemen- this pasty mix was often packed behind tioned; they then round out and enlarge the larva. A similar phenomenon was the opening to the chamber (Krogstad reported in Palearctic species and was 1959). At pupation, the two thoracic res- assumed to indicate that larvae were piratory organs project from the gallery feeding on microorganisms growing on opening and become the primary res- the paste (Mamayev and Krivosheyna piratory organs (Fig. 1g), while the anal 1966, Wood 1981, Krivosheina 2000); siphon shrinks and presumably loses all however, the exact composition of the or most of its respiratory function. larval diet remains unknown. Axymyiid

Fig. 2. Scattergram of cranial measurements for larval Axymyia furcata. iI, 1st instar (n = 18); iII, 2nd instar (n = 9); iIII, 3rd instar (n = 94); iIV, 4th instar (n = 96).

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larvae may also feed on the wood itself, mortality was expected due to injuries as evidenced by the gut often being ﬁlled sustained during extraction of the pupa with particulate wood (Mamayev and from the wood. However, we found it Krivosheyna 1966, Pereira et al. 1982). more difficult to rear extracted pre-pupal Krogstad (1959) reported on the co- fourth-instar larvae to the imago, pre- occurrence of A. furcata and Temnostoma sumably because provision of food is Lepelletier & Serville, a syrphid whose required. Food apparently was not a lim- larvae frequent rotting logs. We also iting factor in rearing larvae and pupae in found this association at many locations, situ from colonized woody debris, which especially in the southern Appalachians. was the most successful rearing method. In most situations, Temnostoma were in Many if not all individuals reared in this sections of the log that were less satu- manner were able to complete develop- rated and contained wood that was less ment and emerge. This included speci- decayed. Other frequent inhabitants of mens reared in incubators as well as “Axymyia logs” were larvae of the tipu- those left at ambient temperature in the loids Lipsothrix Loew and Epiphragma laboratory. In fact, at least two logs from Osten Sacken. When present, Lipsothrix North Carolina that were reared at am- was usually restricted to outer sections of bient temperature provided more than the most saturated part of the log, whereas 100 emerged adults. For one of these Epiphragma seemed to occur in essen- logs, the first male emerged one day after tially the same microhabitat as A. furcata. the log was collected and the first female Collecting and rearing.—As is true for two days later. The last individuals (2 many groups, the key to collecting axy- males and 3 females) emerged on day 14. myiids is to locate suitable habitat and Most males emerged on days 5–9 and microhabitat and to sample appropriately. most females on days 9–11; however, Once the appropriate habitats are found, adults of both sexes emerged through these flies can be quite abundant. Popu- most of this period. lation densities varied greatly within and Although both emergence and Malaise between collecting sites, with the num- traps were used in this study, only the ber of larvae colonizing a single piece latter were successful in capturing adult of wood ranging from a few individuals A. furcata. Malaise traps were effective at to several hundred; e.g., one small log collecting sites in Iowa, North Carolina, (122 cm length and 12.75 cm average and Virginia. In 2007, an Iowa trap yiel- circumference) from Coweeta Hydrolog- ded several adult specimens between ical Laboratory, North Carolina contained the sixteenth of April and the third of 289 specimens. Krivosheina (2000) noted May. Traps set at Coweeta Hydrological comparable densities in Palearctic spe- Laboratory, North Carolina, during short- cies, recording between 50 and 150 larvae term March or April visits from 2006– in logs measuring one meter in length. 2008, yielded a small number of adults. Various methods were successful for Malaise traps placed in a swampy ripar- rearing pupae to adults, though some ian habitat in Virginia also trapped a

Fig. 3. Light micrographs of Axymyia furcata. a, Fourth-instar larva, habitus; b, Fourth-instar larva, in situ; c, Pupa, habitus; d, Pupal exuviae (left) and pupa within minutes of emergence, in situ; e, Adult male, recently emerged and next to pupal exuviae; f, Adult male, habitus; g, Adult females, showing size variation between specimens reared from same log; h, Adult female, habitus.

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small number of individuals (D. Smith larval stage. Based on the presence of pers. comm.). two or three larval instars at any given Larval instars.—Using measurements time and on adults being present for only from the larval head capsule, we con- a short time in the spring, Krogstad firmed that A. furcata has four larval (1959) suspected a two-year life cycle instars (Fig. 2), which is typical of most for A. furcata. Other studies have also nematocerous flies. The mean widths at suggested a semivoltine, two-year life the anterior margin of the head capsule, cycle for this species (Wood 1981) and just posterior to the base of the mandi- other axymyiids (Krivosheina 2000). bles and at the widest portion of the Although most of our data support this head capsules of each instar follow re- prediction, data from some sites suggest spectively: instar I (0.20 mm, 0.24 mm [n = that sympatric univoltine and semivoltine 18]), instar II (0.31 mm, 0.39 mm [n = 9]), populations may exist. This pattern can instar III (0.49 mm, 0.63 mm [n = 94]), be seen in the highly variable size among and instar IV (0.74 mm, 1.01 mm [n = pupae and adults, in which a portion of 96]). Interestingly, A. furcata is unusual the individuals may be noticeably smaller in that the first instar apparently lacks than other individuals from the same log an egg-burster (Wihlm et al. In press), (Fig. 3g). For example, single logs from a structure present in most first-instar North Carolina (Fig. 4a) and New York nematocerous Diptera. (Fig. 4b) yielded some females that were Phenology and adult behavior.—Most strikingly larger (e.g., 6.9–8.0 mm wing of an axymyiid life cycle is spent in its length from NC, 7.6–7.7 mm wing length

Fig. 4. Histogram of wing size and number of emerged Axymyia furcata from individual logs. a, Tributary of Rough Fork, Great Smoky Mountains National Park, North Carolina; b, Tributary of Michigan Creek, Danby State Forest, New York.

from NY) than others (e.g., 5.0–6.5 mm Few reports of adult axymyiid be- wing length from NC, 5.1–6.8 mm wing havior exist. Adults of Palearctic species length from NY). The same pattern was have been observed swarming in slow observed in adults of both sexes in pop- flight on warm sunny days (Krivosheina ulations scattered across the eastern U.S. 2000). This behavior has not been wit- The mechanism for this polymorphism nessed in A. furcata. In lab situations remains unclear. Perhaps smaller in- adults often seem apprehensive to fly dividuals resided in a microhabitat that and prefer to walk, which makes them provided better nutrition, thereby allowing easy to capture. Furthermore, if an adult the larva to move more quickly through takes flight, it is usually quite slow and its development and to pupate in a single clumsy. Although these behaviors are year. Alternatively, smaller individuals perhaps an artifact of laboratory rearing, may have originated from a microhabitat we have several field-collected adults that with lower-quality resources, which stunted were easily captured out of the air by hand. their growth, resulting in a much smaller The adult life span is unknown, but the size at emergence. Our data, which include possession of vestigial mouthparts suggests both large and small adults emerging from these flies are short lived (Wood 1981). In the same region on many logs, seem to our study, laboratory reared adults survived refute the latter alternative. onlyafew(2–7) days. Although we never After overwintering as a larva and just observed oviposition in the field, we re- prior to pupation in the early spring, the corded several females in our rearing larva enlarges the opening of its gallery, chambers that placed eggs individually which will soon be filled by the anterior on logs containing larvae or pupae. end of the pupa (mostly the dorsal part of Conclusion.—Many discoveries about the thorax, with the respiratory organs). axymyiid biology remain for future dip- Prior to eclosion the pupa positions itself terists and aquatic biologists. Historically, so that the head, thorax, and sometimes these flies have been considered quite the anterior-most abdominal segments rare, presumably because adults are sel- project out of the chamber (Figs. 3d). dom seen in the environment and rarely The adult then emerges directly onto the trapped or caught in sweep nets. This surface of the log and may remain near may reflect the short adult lifespan, their the cast skin for several minutes, pre- reluctance to fly, or some other aspect of sumably while the cuticle hardens (Fig. their biology. Regardless, our study has 3e). Adults are known to emerge in April demonstrated that the immature stages, to early May in the Midwest and north- especially the larvae, can be very abun- eastern North America (McAtee 1921, dant in the appropriate habitat. A better Krogstad 1959, Wood 1981, Young and understanding of larval habitat has lead to Lisberg 2001, M. Wihlm and G. Courtney the discovery of many additional pop- unpbl.); however, emergence in the south- ulations of A. furcata. We have clearly eastern United States can begin in early shown that A. furcata is more widespread to mid-March. Adults of the Palearctic in eastern North America than was pre- species have also been recorded to emerge viously thought and that these flies are not in April and May (Krivosheina 2000). rare—they are merely under-collected. Specimen labels indicate that the un- The use of the niche modeling software, described species from Oregon emerges DIVA GIS, predicts that many other areas in November, differing from all other of eastern North America should harbor documented species. these unusual flies. However, as is the

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case for many specialized insects, the key on an earlier version of the manuscript. to future discoveries will be to effectively This project was supported in part by sample their unusual habitats. Axymyiid the National Science Foundation (EF- distributions have undoubtedly been sha- 0334948 and DEB-0933218) to Gregory ped by diverse variables, including not W. Courtney and by the Dean of Agri- only historical factors (e.g., distribution culture and Life Sciences International of their woody host species) but also Research Grant and Biosystematics Travel subtle features of their microhabitat (e.g., Fund to Matthew W. Wihlm. This journal age and orientation of woody debris). Data paper of the Iowa Agriculture and Home from future collections and controlled field Economics Experiment Station, Project and laboratory experiments may test the No. 6693, was supported by Hatch Act relative importance of these and other en- and State of Iowa funds. vironmental variables and provide addi- Literature Cited tional insights into the biology of these xylophilic flies. Alexander, C. P. 1920. The crane flies of New York part II: biology and phylogeny. Cornell ACKNOWLEDGMENTS University Agricultural Experiment Station, Memoir 38: 704–1133. We would like to acknowledge the Alexander, C. P. 1942. Family Anisopodidae. following for their contributions to this Bulletin of the Connecticut State Geological research: Jessica Petersen for her help and Natural History Survey 64: 192–196. with the Diva-GIS 5.2 software, Jesse Bertone, M. A., G. W. Courtney, and B. M. Wiegmann. 2008. Phylogenetics and tempo- Randall for identifying the trees at our ral diversification of the earliest true flies collecting sites, Douglas Stokke for iden- (Insecta: Diptera) based on multiple nuclear tifying wood samples (i.e., larval micro- genes. Systematic Entomology 33: 668–687. habitat), Brian Preston and the staff at the doi:10.1111/j.1365-3113.2008.00437.x. Swiss Valley Nature Center for tending Courtney, G. W. and R. W. Merritt. 2008. Aquatic Malaise traps, Brian Kloeppel and Jason Diptera: Part one: Larvae of aquatic Diptera, pp. 687–722. In R.W.Merritt,K.W.Cummins, Love for permission to collect at Coweeta and M. B. Berg, eds. An Introduction to the Hydrological Laboratory, Charles Parker Aquatic Insects of North America. Fourth Edi- for permission to collect at Great Smoky tion. Kendall / Hunt Publishing Co., Dubuque, Mountains National Park, and Peter Adler, Iowa. 1158 pp. Clemson University, for permission to Courtney, G. W., B. J. Sinclair, and R. Meier. 2000. Morphology and terminology of Dip- collect at Issaqueena Forest, South Caro- tera larvae, pp. 85–161. In L. Papp and B. lina. In addition, we thank the CNC (J. M. Darvas, eds. Contributions to a Manual of Cumming and D. M. Wood), Cornell Uni- Palaearctic Diptera, Volume 1. Science Her- versity Insect Collection (J. K. Liebherr), ald, Budapest. 978 pp. Museum of Comparative Zoology Dudley, T. and N. H. Anderson. 1982. A survey of (P. Perkins), USNM (D. R. Smith and W. invertebrates associated with wood debris in aquatic habitats. Melanderia 39: 1–21. N. Mathis), University of Guelph Insect Hijmans, R. J., L. Guarino, A. Jarvis, R. O’Brien, Collection (M. Buck and S. A. Marshall), P. Mather, C. Bussink, M. Cruz, I. Barrantes, University of Minnesota Insect Collec- and E. Rojas. 2005. DIVA-GIS. version 5.2. tion (P. J. Clausen), and University of A Geographic Information System for the Wisconsin’s Insect Research Collection Analysis of Species Distribution Data. Man- ual available at http://www.diva-gis.org/. (S. Krauth and D. K. Young) for the loan Hiroshi, I. 1953. A new Pachyneuridae from of comparative material. We also thank Japan (Diptera). The Scientific Reports of the Art Borkent for his valuable suggestions Saikyo University, Agriculture 5: 117–118.

Krivosheina, M. G. 2000. Family Axymyiidae, D. M. Wood, coords. Manual of Nearctic pp. 31–39. In L. Papp and B. Darvas, eds. Diptera, Volume 3. Agriculture Canada Mono- Contributions to a Manual of Palaearctic graph 32. Diptera, Appendix. Science Herald, Buda- Yang, J. 1993. The family Axymyiidae new to pest. 604 pp. China with a new species (Diptera: Nem- Krogstad, B. O. 1959. Some aspects of the ecol- atocera) from Guizhou. Entomotaxonomia ogy of Axymyia furcata McAtee (Diptera, 15: 319–322. Sylvicolidae). Proceedings of the Minnesota Young, D. K. and A. Lisberg. 2001. First record Academy of Sciences 27: 175–177. of Axymyiidae (Diptera: Nematocera: Ax- Mamayev, B. M. 1968. New Nematocera of the ymyioidea). Great Lakes Entomologist 34: USSR (Diptera, Axymyiidae, Mycetobiidae, 7–8. Sciaridae, Cecidomyiidae). Entomologicheskoe Zhang, J. 2010. Two new genera and one new Obozrenie 47: 607–616. [In Russian, trans- species of Jurassic Axymyiidae (Diptera: lation in Entomological Review 47: 371– Nematocera), with revision and redescription 377] of the extinct taxa. Annals of the Entomo- Mamayev, B. M. and N. P. Krivosheyna. 1966. logical Society of America 103: 455–464. New data on the taxonomy and biology of doi:10.1603/AN09073. the family Axymyiidae (Diptera). En- tomologicheskoe Obozrenie 45: 168–180. [In Appendix 1. Records of Axymyia furcata Russian, translation in Entomological Re- from recent collections in the United view 45: 93–99] McAtee, W. L. 1921. Description of a new genus States. States listed in bold indicate = of Nemocera (Dipt.). Proceedings of the En- new state records. CHL Coweeta tomological Society of Washington 23: 49. Hydrological Laboratory, GSMNP= Oosterbroek, P. and G. W. Courtney. 1995. Phy- Great Smoky Mountains National Park, logeny of the nematocerous families of and IF=Issaqueena Forest (Clemson Diptera (Insecta). Zoological Journal of the University). Linnean Society 115: 267–311. Papp, L. 2007. Dixidae, Axymyiidae, Myceto- Connecticut: Litchfield Co: Macedonia biidae, Keroplatidae, Macroceridae, and Di- Brook State Park, 41˚45.66’N 73˚ tomyiidae (Diptera) from Taiwan. Acta 29.71’W. Zoologica Academiae Scientiarum Hungar- Georgia: Rabun Co: Warwoman Dell, icae 53: 273–294. Pereira, C. D. R., N. H. Anderson, and T. Dudley. 34˚52.88’N 83˚21.15’W; Towns Co: 1982. Gut content of aquatic insects from Charlie’s Creek above Tallulah River, wood substrates. Melanderia 39: 23–33. 34˚57.67’N 83˚33.54’W. Peterson, A. 1960. Larvae of Insects, An Intro- Iowa: Dubuque Co: tributary of Catfish duction to Nearctic Species. Part II: Coleoptera, Creek, Swiss Valley Nature Center, 42˚ Diptera, Neuroptera, Siphonaptera, Mecoptera, 25.31’N 90˚45.44’W; farm creek near Trichoptera. Edwards Brothers, Inc., Ann town of Durango, 42˚33’N 90˚46’W. Arbor, Michigan. 416 pp. Kentucky; Letcher Co: Bad Branch, 37˚ Wihlm, M. W., R. B. Sam, and G. W. Courtney. In press. Morphology of Axymyia furcata 04.20’N 82˚46.30’W; Rockcastle Co: McAtee (Diptera: Axymyiidae), including small creek NE of Livingston, 37˚17’N scanning electron microscopy of all life 84˚12’W. stages. The Canadian Entomologist. Maine: Oxford Co: White Mountain Wood, D. M. 1981. Axymyiidae, pp. 209–212. In National Forest, 44˚22.48’N 70˚59.36’W; J. F. McAlpine, B. V. Peterson, G. E. Shewell, tributary of Bog Brook @ Bog Road, H. J. Teskey, J. R. Vockeroth, and D. M. Wood, 44˚22.91’N 70˚54.29’W; Maryland: coords. Manual of Nearctic Diptera, Volume 1. Frederick Co: Buzzard Branch @ Mink Agriculture Canada Monograph 27. Wood, D. M. and A. Borkent. 1989. Phylogeny Farm Road, 39˚35.22’N 77˚29.60’W; and classification of the Nematocera, pp. 1333– Garret Co: Savage River State Forest, 1370. In J.F.McAlpine,B.V.Peterson,G.E. 39˚35.19’N 79˚10.16’W; Massachusetts: Shewell,H.J.Teskey,J.R.Vockeroth,and Franklin Co: Mount Toby State Forest,

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42˚29.33’N 72˚31.48’W; Mount Sugarloaf GSMNP, tributary of Palmer Creek, 35˚ State Reservation, 42˚28.94’N 72˚34.94’W; 37.70’N 83˚06.90’W. Minnesota: Clearwater Co: Itasca State Ohio: Hocking Co: Hocking Hills State Park, 47˚13.72’N 95˚11.02’W. Park, 39˚27.54’N 82˚33.52’W. New Hampshire: Grafton Co: White Pennsylvania: Clinton Co: Hyner Run Mountain National Forest, 44˚04.22’N 71˚ State Park, 41˚21.97’N 77˚37.86’W; Kettle 41.68’W; New York: Tompkins Co: Danby Creek State Park, 41˚20.54’N 77˚54.54’W. State Forest, 42˚18.92’N 76˚29.69’W; South Carolina: Oconee Co: small trib- Danby State Forest, 42˚17.80’N 76˚ utary of Brasstown Creek, 34˚43.15’N 83˚ 28.97’W. 18.24’W; Pickens Co: IF, Indian Creek, North Carolina: Macon Co: CHL, Hugh 34˚45.55’N 82˚51.45’W; IF, Wildcat Creek, White Creek (WS 14), 35˚03.28’N 83˚ 34˚45.35’N 82˚51.38’W; IF, small tributary 25.90’W; CHL, Grady Branch (WS 18), of Six-Mile Creek, 34˚44.86’N 82˚51.25’W. 35˚03.07’N 83˚26.17’W; CHL, seeps near Tennessee: Sevier Co: GSMNP, small Ball Creek gate, 35˚03.53’N 83˚25.82’W; creek near Husky Gap trail, 35˚39’N 83˚ CHL, upper Reynolds Branch, 35˚02.30’N 31’W. 83˚27.10’W; CHL, Cold Springs Gap Vermont: Bennington Co: Green Mountain seeps, 35˚01’N 83˚27’W; CHL, Bates National Forest, 43˚02.56’N 73˚05.48’W. Branch, 35˚03’N 83˚27’W; CHL, small Virginia: Fairfax Co: Great Falls Na- creek above weir 16, 35˚03’N 83˚26’W; tional Park, 38˚59.10’N 77˚14.80’W. CHL, 35˚02’N 83˚27’W; Haywood Co: West Virginia: Nicholas Co: Mono- GSMNP, seeps near Cataloochee Creek, ngahela National Forest, 38˚18.01’N 80˚ 35˚38.75’N 83˚04.56’W; GSMNP, seeps 30.61’W; Monongahela National Forest, near Rough Fork, 35˚36.90’N 83˚07.26’W; 38˚16.24’N 80˚31.46’W.