SAMPLING,DISTRIBUTION,DISPERSAL Distribution of the Brown Recluse Spider (Araneae: Sicariidae) in Georgia with Comparison to Poison Center Reports of Envenomations 1,2 3 4 RICHARD S. VETTER, NANCY C. HINKLE, AND LISA M. AMES J. Med. Entomol. 46(1): 15Ð20 (2009) ABSTRACT Georgia is on the southeastern margin of the native range of the brown recluse spider, Loxosceles reclusa Gertsch and Mulaik. The brown recluse is not a common Georgia spider and has limited distribution in the state. Using recent submissions, previously published records, and exam- ination of museum specimens, we document the spiderÕs presence in 31 (19.5%) of GeorgiaÕs 159 counties, with almost all being found in the northern portion. The spider was collected almost exclusively north of the Fall Line (a transition zone separating the Piedmont and the Coastal Plain geological provinces). Only two locations in the southern Coastal Plain province produced L. reclusa specimens; these southern Þnds are considered spiders that were transported outside their range. There were six Þnds of the non-native world tramp species, L. rufescens (Dufour), three south of the Fall Line. In conspicuous contrast, over a 5-yr period, a Georgia poison center database recorded 963 reports of brown recluse spider bites from 103 counties. These Þgures greatly outnumber the historic veriÞcations of brown recluses in the state for both specimen quantity and county occurrence, indicating improbable spider involvement and the overdiagnosis of bites. In the southern half of the state, medical diagnoses of brown recluse spider bites have virtually zero probability of being correct. Bite diagnoses should be made with caution in north Georgia given the spiderÕs spotty distribution with low frequency of occurrence. KEY WORDS Loxosceles reclusa, brown recluse spider, Arachnida, distribution, overdiagnosis The brown recluse spider, Loxosceles reclusa Gertsch Chamberlin and Ivie (1944) listed 350 spider species and Mulaik, is well known for causing dermonecrotic from the “Georgia area” (most of Georgia and South lesions in humans. Its native range is the south and Carolina) with the brown recluse not among them, central midwestern United States (Gertsch and Ennik supporting the notion that the spider is an uncommon 1983, Swanson and Vetter 2005, Vetter 2008), and it is entity in both states. Gorham (1968a) described col- rarely found outside of this distribution (Vetter and lections of L. reclusa from 4 of GeorgiaÕs 159 counties Bush 2002a, b, Vetter 2005, 2008). Despite the infamy (Fulton, Oglethorpe, Spalding, Walton), with a cor- of the spider and exaggerated claims of supposed en- rection of one county locality (Pike not Spalding) and venomations, there is a surprising paucity of informa- one addition (Paulding) in Gorham et al. (1969). A tion regarding its distribution in many states (Vetter nationwide map veriÞes brown recluse spiders in eight 2008). The southeastern margin of the endemic area of Georgia counties (adding Coweta, Douglas, Spalding) L. reclusa runs through central Georgia (Gertsch and (Cooperative Economic Insect Report 1971). Howell Ennik 1983, Swanson and Vetter 2005). It is readily (1974) lists 12 counties (adding Butts, Cobb, Gordon, found in Tennessee to the north and Alabama to the Henry, and Troup but omitting Oglethorpe) from west (Cooperative Economic Insect Report 1971, Vet- which brown recluse spiders have been recovered. In ter 2008) but is not native to nor often found in Florida the most recent taxonomic revision of the genus, to the south (Vetter et al. 2004). Therefore, brown Gertsch and Ennik (1983) mentioned that specimens recluse spiders are likely to be native to north Georgia were collected from 12 Georgia counties but list only but absent in the southern portions, with a zone of 2 (Cobb, Henry). Swanson and Vetter (2005) showed attrition somewhere in between. the range of the brown recluse as including the north- western portion of Georgia based on the sparse infor- mation mentioned above. Reports of envenomations from brown recluse spi- 1 Corresponding author: Department of Entomology, University of California, Riverside, CA 92521 (e-mail: [email protected]). ders, both diagnoses by the medical community and 2 Division of Biology, San Bernardino County Museum, Redlands, self-assessments by the nonmedical general public, CA 92373. occur throughout North America despite the rarity or 3 Department of Entomology, University of Georgia, Athens, GA nonexistence of the spider over much of the continent 30602. 4 Department of Entomology, University of Georgia, GrifÞn Cam- (Vetter and Bush 2002b, Vetter et al. 2003, 2004, Ben- pus, GrifÞn, GA 30223. nett and Vetter 2004, Swanson and Vetter 2005, Frith- 0022-2585/09/0015Ð0020$04.00/0 ᭧ 2009 Entomological Society of America 16 JOURNAL OF MEDICAL ENTOMOLOGY Vol. 46, no. 1 sen et al. 2007, Vetter 2008). Medical authors cite From museums, one of us (R.S.V.) requested brown spider bite data from the annual report of poisonings recluse spider specimens (either the entire collection and injuries from the American Association of Poison if small or just Atlantic seaboard state specimens if the Control Centers (AAPCC) (see Vest 1996 for an ex- collection was large) from the following: American ample). Although AAPCC data are fairly reliable for Museum of Natural History (New York, NY), National conditions where the causative agent is readily deter- Museum of Natural History (i.e., Smithsonian; Wash- minable (e.g., snake bite, acetaminophen poisoning), ington, DC), Field Museum of Natural History (Chi- the data for spider bite reports are virtually useless cago, IL), California Academy of Sciences (San Fran- (Vetter and Furbee 2006). For example, Florida has no cisco, CA), Denver Museum of Nature and Science native Loxosceles populations of any species and Þnds (Denver, CO), Florida State Collection of Arthropods are both very rare and highly circumscribed. How- (Gainesville, FL), Burke Museum of Natural History ever, from a 6-yr AAPCC database from the three (Seattle, WA), and Clemson University Arthropod Florida poison centers, 85% of the 844 reports of Museum (Clemson, SC). The Georgia Museum of Loxosceles envenomations were made by nonmedical Natural History was also searched. personnel and originated from Ϸ75% of its counties Putative spider bite data were procured from the (Vetter et al. 2004). Unfortunately, medical authors Georgia Poison Center, which provided a 5-yr data set incorrectly use the AAPCC data set to substantiate for brown recluse bite reports in Georgia. The infor- brown recluse spider presence in an area by virtue of mation included data of bite report, county if known, bite reports without realizing that the general public and age and sex of the alleged bite victim. However, makes the majority of the reports to poison centers. this data set did not provide sufÞcient data breakdown Because of the high proÞle status of the brown to separate categories between medical and nonmed- recluse spider and the overdiagnoses of Loxosceles ical sources as was done in other studies for Florida bites by medical personnel from areas of North Amer- (Vetter et al. 2004) and Pennsylvania (Vetter et al., ica lacking the spiders, we performed a survey in unpublished data). Georgia to determine the distribution of the spider in greater detail than has been attempted before. We also Results compared the known distribution and quantity of Loxosceles spiders in Georgia to a 5-yr database for bite We provide evidence of brown recluse spiders in 31 reports made in the state. (19.5%) of GeorgiaÕs 159 counties (Table 1; Fig. 1), with almost all Þnds being restricted to the northern third of the state. Published records indicate brown recluse spiders being veriÞed in 13 counties; we un- Materials and Methods covered L. reclusa in 23 counties, 18 of which were Spider specimens were procured from various previously not listed as having these spiders. Although sources. In 2002, a website was established on the it would be more informative to present information Department of Entomology webpage at the University such as the number of recluse spiders found per of Georgia announcing the Georgia Brown Recluse county compared with the total number of spiders Project and the desire for spider submissions. One of submitted, this is not feasible considering the varied us (N.C.H.) presented seminars to the pest control methods by which the data were generated. Addition- industry throughout Georgia soliciting submissions ally, because of the low Þnal number of recluses (Ϸ100 and, through the media (radio and newspaper inter- specimens), percentages of spiders per county would views), requesting samples from the general public. vary wildly and provide almost no coherent biological Another author (L.M.A.) is the arthropod identiÞca- meaning. tion specialist at the diagnostic laboratory of the Geor- One submission was a male L. reclusa involved in a gia Experiment Station of the University of Georgia veriÞed bite incident near Rome (Floyd County). and receives arthropods from throughout the state. Brown recluse spiders have been veriÞed in two lo- Several Loxosceles datapoints were recovered from the cations from the southern half of Georgia. One site was Distance Diagnostics through Digital Imaging system, a woodworking shop in Brunswick (Glynn County) which is a mechanism for University of Georgia ex- with several specimens collected (transported lumber tension specialists to submit electronic images and from Alabama was the suspected mechanism of move- obtain quick identiÞcations. Records are stored in a ment) and the other, from Warner Robins (Houston permanent database; Loxosceles records were re- County), was intercepted from household goods be- trieved along with collection information. Additional ing unpacked by a couple who had moved from Ten- data were generated by a 5-yr study that offered to nessee. Many of the county records that we present identify any spider thought to be a brown recluse here are Þnds of single specimens, each being the only (Vetter 2005).