Bites by the brown spiders Loxosceles unicolor and Loxosceles arizonica in California and Arizona

Toxkon, 1%9, VOI. 7. pp . I114-I17 . Per~mon Prw. Printed In C3reat Hriteln

BITES BY THE BROWN SPIDERS LOXOSCELES UNICOLOR AND LOXOSCELES ARIZONICA IN CALIFORNIA AND ARIZONA FYxnLAY E. RUSSELL, WILLIAM G. WALDRON and Mürroo B. MAnox Los Angeles County-University of Southern California Medical Center, Los Angeles County Health Department, and State of California Department of Public Health, Los Angeles, California, U.S .A . (Acceptedjor publication 8 February 1969) RussEI,L and WALDRON (1967) listed 15 species of spiders, in addition to the black widow Latrodectus mactons, which were implicated in 73 bites on humans in Southern California during the 11-year-period 1955-1966. They note that an additiona1487 uses of suspected spider bite were reported to them in the area during the same period, but point out that many of these may have been caused by arthropods other than spiders, particularly fleas, ticks, bedbugs and biting flies. They discuss some of the clinical manifestations of spider venom poisoning in Southern California and caution against implicating the brown spider, Loxosceles reclusa, as the offending culprit in `necrotic arachnidism' in the area. Since publication of their letter, an additional 16 cases of suspected spider bite have been seen at the Los Angeles County-University of Southern California Medical Center, and 28 more by the authors in other southland hospitals and clinics. The majority of these bites were inflicted by the black widow spider, L. atrodectus muctans [L. mactans hesperus ( ~], or unknown species. Three bites were due to tarantulas, two to Phidippusformosus, two to Steatoda grossa, one to Chiracanthium sp ., and one to a `jumping spider' Thiodina sylvana (WALDRON, 1968). Three cases of necrotic arachnidism were seen. This brings to a total of 15 the cases of necrotic arachnidism, not unlike those described for L. reclusa envenomation, observed by the authors during the past 14 years. In three of these cases the offending spider was Loxosceles unicolor, and in one case the spider was Loxosceles arizonica. In six cases the account of the spider and the clinical syndrome were descriptive enough to suspect L. unicolor, and in one case L. arizonica. In the remaining four cases the offending spider would not appear to have been a Loxosceles species. In fact, in two cases the offending spider was later identified . These cases will be reported elsewhere. The purpose of the present report is to describe three cases of known and two cases of probable L. unicolor envenomation, and one case of known and one case of probable L. arizonica envenomation, and to demonstrate the lesionsthat can be produced experimentally by these spiders. Case 1 A 32-year-old train brakeman was bitten on the dorsum of the right hand by a `light brown spider with long spindly legs' while checking a boxcar on a siding at Colton, Cali fornia . He crushed the spider and put it in his wallet. There was some slight pain at the time 109

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FINDLAY E. RUSSELL, WILLIAM G. WALDRON and MINGO B. MADON

of the bite but no further discomfort until 3 hr later, when the patient complained of a dull aching sensation in his right arm. At that time he noted a small `pimple', surrounded by an ischemic area which in turn was outlined by an erythematous ring . The entire lesion `itched terribly'. Several hours later he complained of pain `up the arm' and into the axilla . When seen in Los Angeles 18 hr later he complained of pain in the right hand, arm and axilla, chills, headache, nausea and generalized weakness. Physical examination revealed a tender lesion having a central vesicle of 1 cm in diameter, the base of which was hemorrhagic ; it was demarcated by a thin ridge of dark tissue, which in turn was surrounded by an irregular blanched area having the appearance of a blister (Fig . 1) . There was some edema of the dorsum of the hand, and axillary lymphadenopathy . His temperature was 99'8 ° F, pulse 82 and blood pressure 140/80 mm of mercury . Urine and blood analyses and the electrocardiogram were normal . The vesicle was ruptured, the lesion debrided and covered with a sterile dressing. The patient was placed on a wide-spectrum antibiotic . The following day the ulcer crater had enlarged, although the edema had decreased. A small area of erythema was present around the lesion . When next seen, 4 days later, the ulcer crater was 2~5 cm in diameter and ringed by a margin of erythema . A dark eschar was removed. No pathogenic organisms were isolated . At this time more extensive debridement was done and the patient placed on metronidazole (RUSSELL, 1966). The lesion healed without complications in 17 days . The spider's body was crushed beyond recognition . However, the length and other features of the legs made it possible to identify the spider as L. trnicolor. Case 2 A 22-year-old electrician was bitten on the dorsum of the left hand by L. unicolor while cleaning lumber near Blythe, California . The spider was killed and placed in a jar. There was no initial pain. Four hours later the injured area began to `itch', and a small erythematous area was seen around the bite area . The area became tender and the hand painful. The patient was referred to the Medical Center on consultation. When seen 8 hr following the bite the patient complained of intense pain over the dorsum of the left hand and along the medial aspect of the forearm. He also complained of nausea and weakness . Physical examination revealed a 3 mm vesicle bounded by an irregular blanched area, which in turn was surrounded by an erythematous zone on the dorsum of the left hand . Linear lymphangitis was observed on the left forearm. The axillary lymph nodes were not enlarged, but theaxilla was tender . There were no other significant physical findings . Laboratory tests were normal. The wound area was surgically excised and the patient placed on an oral corticosteroid . Because of the distance between Los Angeles and Blythe the patient was referred to a physician in the Blythe area . Unfortunately, the patient decided to leave on a 10-day trip into Baja, California the following day and departed without further medical attention. He continued the corticosteroids as directed for 9 days, redressed the wound every third day, and just to make sure, put himself on an oral antibiotic for 1 week . In spite of the regime, there were no complications. He later stated that the excised area formed a scab which was dark in colour, and that the scab separated at 20 days leaving a small ulcer. Fig. 2 shows the lesion area 6 weeks following the bite . The spider was sent by the patient's wife the day after the accident and was identified as a female L, unicolor .

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Case 3 A 44-year-old painter from Saugus, California, was bitten by L. unicolor while carrying old lumber on his shoulder. He felt a `sting' on his left chest and after setting the lumber down opened his shirt and found a'brown spider', which had been slightly squashed and was dead. He put the spider in a cigarette package and continued his work. About 30 min later he noted pain over the entire left chest and neck, nausea, chills, malaise, and pain on moving his left shoulder and neck. The pain increased in severity and a small bleb formed at the wound site. In spite of the pain he did not call a physician for 8 hours. The patient was given an antihistamine, a `shot for tetanus, some pain pills and a shot of penicillin' . The following day the patient noted a vesicle `filled with blood' at the bite site. This was surrounded by a `white ring'. Outside the white ring the tissues were `red, tender and swollen'. The patient still had some pain over the chest, left shoulder and neck. He returned to his physician who gave him further penicillin and an ointment to put on the lesion. On the fourth day after the bite the patient was seen by one of us. An irregular lesion measuring 3 cm in length and 1 cm in width, and having a depressed hemorrhagic center demarcated by a dark border, was found. The lesion was extremely tender to touch and some tenderness was present over the left chest . The skin temperature about the lesion was elevated, and a scarlatiniform-like rash was present over the chest, neck, left shoulder and arm . Physical examination revealed a pulse of 92 and blood pressure of 150/84 mm of mercury . Blood and urine analyses were normal . The spider was identified as L. unicolor . The lesion was surgically excised . (Unfortunately, the photographs of the lesion were spoiled, and it was not until 3 days later that this was discovered . Another photograph was then taken, Fig. 3). The necrotic parts of the lesion extended deep into the subcutaneous tissues, necessitating the use of a drain. Drainage continued for 6 days and an attempt to close the wound on the eighth post-operative day was unsuccessful. A successful skin graft was made 4 weeks later. A microscopic study ofthis lesion will be reported elsewhere . Case 4 A 28-year-old male was bitten on the left leg by a female L. arizonica while collecting arthropods in a rubbish pile on the outskirts of Tucson, Arizona. The patient stated the bite was no worse than that of an ant sting, and that the pain went away almost immediately . However, the area became quite painful within an hour, and the patient complained of generalized tenderness and an increase in skin temperature over the area. The patient drove to Los Angeles and was seen by one of us approximately 12 hr after the bite. Figure 4 shows the lesion. At the center is a hemorrhagic puncta surrounded by an irregular zone of ischemia, which in turn is surrounded by a ring oferythema . In the erythematous area are several small blebs filled with a clear fluid. The area about the lesion was indurated and tender . All laboratory findings were normal. The area was excised and immediately treated with fibrinolysin and desoxyribonuclease, combined (bovine) Elase® . The ointment was applied daily for the subsequent 8 days. Healing was complete within 3 weeks . Case 5 About eight or nine years ago one of us was called to see a patient in San Gabriel Valley . The patient stated he had been bitten by a spider some days before and that the lesion had grown until it appeared as shown in Fig. 5. Unfortunately, our records of the case as well as the names of the attending physician and patient were lost in an aircraft fire in 1965, and we have been unable to locate the physician for details on the case . When first seen by one

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FINDLAY E. RUSSELL, WILLIAM G. WALDRON and MINOO B. MADON

of us the lesion looked as shown in the photograph. Loss of tissue had extended to the muscle. The initial lesion was described as a small painful vesicle surrounded by erythema. The lesion gave rise to ulceration and extensive necrosis . The patient said he had been bitten by a spider that was `long-legged and brown', and that it had probably been in the wall or floor he was in theprocess of repairing. At the time it did not seem possible to us that such a lesion could be produced by the venom of a spider in California . We had seen several small ulcerative lesions caused by spiders prior to this case, but we had not seen any tissue changes of this severity. However, there was no question in the mind of the patient or the attending physician that the lesion was a direct result of the spider bite . We trust that the physician in charge will recognize the photograph and provide more details on this case . We now suspect that the offending spider was a Loxosceles species.

Case 6

A 33-year-old female was bitten over the medial malleolus of the left ankle while in or just outside her home near Blythe, California . She did not feel the bite nor note the animal that bit her. She complained of an itching sensation about the left ankle and subsequently noted a `small boil', which became encrusted and eventually ulcerated. The ulcer was approximately 2 cm across . Figure 6 was taken approximately 14 days after the original lesion developed . The center of the lesion was depressed and had a hemorrhagic base. The edges were dark and there was an irregular area of erythema . The ankle was slightly edematous. The patient stated she had seen `several brown spiders' in and around her house. Further consultation with Dr . J. P. Barry, who had seen the patient, indicated the lesion was very similar to others he had seen in patients from the Blythe area. L. unicolor is apparently not uncommon in this part of Southern California . He noted that in almost all of the cases he had seen that the bites had been on the legs or feet . Case 7 In 1955, a 46-year-old surveyor working on a road near Tempe, Arizona was bitten by a `small gray-brown spider with long legs'. He had been working in a pile of old lumber most of the day. He felt the bite, saw the spider and killed it, and then returned to work . Twenty minutes later the area of the bite on the right thigh became painful and slightly tender . He did not check the injured area for several hours. When he did he found a small irregular bleb at the bite site. This was filled with a fluid he thought might have been blood. His leg ached and he had some right inguinal pain. He became nauseated, complained of chills and felt very weak . One of us spoke with the patient by telephone 8 hr after the bite and referred him to Dr. F. A. Shannon of Wickenburg, Arizona. A letter from Dr. Shannon, dated October 23, 1955, states the patient had a `gangrenous but dry hard granular lesion the size of a penny' which `eventually sloughed out leaving a crater'. At the time of the injury we advised Dr. Shannon to try steroids, which according to the patient he did. A 10-day course of steroids was given. The lesion took 6 weeks to heal . Figure 7 shows the ulcer area 2 years after the bite. When shown a tray of 30 spiders from Arizona and California, one of the three spiders the surveyor identified as the possible culprit was Loxosceles arizonica. EXPERIMENTAL Initial attempts to induce L. unicolor and L. arizonica to bite small animals were unsuccessful . Only by heating them slightly as they recovered from an anesthetic, or irritating

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FIG. S . MARKED TISSUE DESTRUCTION ATTRIBUTED TO THE BITE OF AN UNKNOWN `LANG-LEGGED, BROWN SPIDER' IN SOUTHERN CALIFORNIA .

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Loxosceles Bites

113

them with a blast of air in a confined area, could we get these spiders to bite into the skin of a rabbit's ear or the abdomen of a mouse. (In milking these arthropods we generally tease their fangs and mouth parts and then take the venom from the tips of the fangs with a micropipette .) After teasing and several blasts of air we were able to induce a large female L. unicolor into biting the ear ofa rabbit . The sequence ofchanges is shownin Fig. 8. At 8 hr there was a lesion of 7 mm in diameter. It was white, slightly elevated, with grey, raised edges, and resembled a crust. It was surrounded by an area of hyperemia, measuring 14 mm in width. The tissues adjacent to the hyperemic area were only slightly swollen and faintly red. The skin was intact. The entire lesion was sharply demarcated from the surrounding tissues. Sixteen hours following the bite the center of the lesion was white and depressed. The edges appeared rolled, and the hyperemic area was wider and more irregular. The surrounding tissues were slightly more swollen and red. At 24 hr there was a hemorrhagec area near the center of the white, depressed lesion . The surrounding hyperemia radiated irregularly from the rolled edges to 20 mm from the center of the lesion . There were a few petechial hemorrhages in this area . The area around the lesion was red and swollen. At 32 hr the entire ear was red, and so markedly edematous that the rabbit could not hold it erect. It was even more red and more swollen at 48 hr, and the area of hyperemia about the central lesion was now marked and contained several areas of hemorrhage. The hemorrhagec area near the center ofthe white lesion was now 5 mm across, and in one area had perforated the skin. Otherwise, the skin over the entire lesion was still intact . The skin temperature of the ear was markedly increased. On the fourth day a dark eschar developed over the hemorrhagec area at the center of the lesion . When the eschar was lost, a dark, well-healed ulcer crater was observed. The ulcer was subsequently scratched rather violently by the rabbit, but surprisingly enough it did not bleed. Four weeks after the bite the area was excised for histological studies. At that time there was a dark, well-healed ulcer with slightly rolled edges. Attempts to induce L. arizonica to bite the ear of a rabbit were as time consuming as with L . unicolor. A 9 mm female L. arizonica was seen to bite into the skin of a rabbit's ear. The local changes during the first 12 hr following the bite were very similar to those we have described for L. taiicolor. At 18 hr following the bite the central part of the lesion measured 11 mm across (Fig. 9). It was only slightly raised and blanched . The area immediately surrounding this was hyperemic and indurated, with several areas ofpetechial hemorrhage nearthe edges ofthe blanched centrallesion. Two small areas ofhemorrhage were observed near the inferior margin of the lesion . These may have been where the spider had bitten . The entire ear was red and swollen. This was particularly evident around the bite area. The animal could not hold its ear erect. The skin temperature was markedly elevated . Unfortunately, the black and white photographs do not show the degree of swelling and redness seen on our colored prints. Twenty-seven hours following the bite a superficial ulcer of approximately 8 mm in diameter, and having several hemorrhagec areas, developed near the center of the white lesion, which was now more clearly demarcated than at 18 hr. The edges of the central white area were slightly raised, firm and hyperemic . The entire ear was red and swollen, and the animal was lethargic. He did not eat but appeared to take in more water than normal . His re$exes, blood pressure and pupils were normal . Two days following the bite the entire central white area had ulcerated leaving a lesion of 14 mm in diameter (Fig. 9). The ulcer had a hemorrhagec base, part of which was covered

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FINDLAY E. RUSSELL, WILLIAM G. WALDRON and MINOO B. MADON

by a dark eschar. The edges of the ulcer were dark, raised and firm, and the surrounding tissues were still red and swollen. One week later the ulcer was well healed . The tissues of the base of the ulcer were very dark, and the edges were irregular but unremarkable. There was little edema or redness of the ear and the rabbit could hold the ear erect. A scab subsequently formed over the ulcer and was apparently broken off by the rabbit . Three months after the bite the animal was perfectly normal except for an ulcer of 12 mm in diameter at the area ofthe bite . The ulcer was dark in color, somewhat firm and did not bleed on superficial abrasion. DISCUSSION

The spiders belonging to the genus Loxosceles are distinguished by their brown color, a body of approximately 5 to 10 mm in length, comparatively long legs, and six eyes in three diads arranged in a semicircle . The violin or fiddle-shaped marking on the dorsal side of the carapace is generally quite distinct, although it may be quite faint in some species. GERTSCi1 (1958) notes that in L. unicolor, adult females vary in length from 6 to 9 mm and have much longer legs than in L. reclusa. The female specimens we have captured average 7 mm iii length and are light brown in colour, sometimes with a shading toward beige or yellow . Males are slightly smaller than the females. L. arizonica is said to be darker in color than L. unicolor but our specimens of the two species appear to be very similar. Specimens from arid regions, however, tend to be paler. The violin markings are very clear in all specimens we have collected (Fig. 10). L. unicolor is known to occur in parts of California, Arizona, New Mexico, Nevada, Utah and Texas (GEx~rscx, 1958). We have collected specimens near Blythe, in downtown San Bernardino, near Calico, near Vidal, near Parker Dam, near Borrego Springs, near Palmdale and Mojave, and near Blackwells Corner in Kern Country. Almost all of these specimens were taken from under ground cover, chiefly lumber, rocks or debris, and generally near human habitation . They were also found inside houses . They appear to live a solitary type of life. Their escape movements are quick, and they are chiefly nocturnal. It is now evident that both L. unicolor and L. arizonica are capable of penetrating the human skin and ofinflicting a bite which gives rise to pain, bleb formation, erythema, and ecchymosis and necrosis leading to eschar and ulceration . However, neither the skin re sponse to the bite nor the systemic changes appear to be as severe as those produced by the venom of L. reclusa. Onthe other hand, ifsome of the lesions we have seen can be attributed to the bite of L. unicolor, and one thought to be due to the bite of this spider as reported by JAMES et al. (1961), then this spider is capable of inflicting a very dangerous wound, and its bite should be considered serious. Bites by L. unicolor appear to be more common than we had expected . While preparing this manuscript we contacted nine physicians who had seen lesions similar to those reported herein. Dr. J. P. Barr y of Blythe has seen a number in Riverside County . His descriptions of the lesions and his experiences are similar to ours. Dr. M. A. Fowler saw three such lesions following spider bites near Palmdale at a summer camp in 1966 . A forestry worker said his physician had seen two such lesions in patients bitten near Riverside, and three other physicians reported possible L. unicolor bites in San Diego and Riverside counties . Dr. H. P. Limbacher of Tucson has probably seen more cases of possible L. arizoníca bites than any other physician. Like most of us, he has been seeing such lesions for 10 or more years, but only after conversations between ourselves have we become aware that L. arizonica ís

Loxosceies Bites

11 5

Nrobably the offending spider in that area. Dr. Limbacher notes (personal communication, 12 November 1968) that in his cases the lesions have sloughed with some loss of tissue, but the patients have had no systemic manifestations of note. Dr. F. A. Shanno n saw one possible L. arizonica bite in addition to Case 6. It is hard to decide what to say about the other cases of `necrotic arachnidism' that have been reported to us during the past decade . In most ofthese instances we have investigated the reports in some thoroughness, and in no case has the suspected arthropod been captured or identified . There is no doubt that some of the lesions have been due to bites by spiders, probably one of those we have previously noted (RUSSELL and WALDRON, 1967 ; WALDRON, 1968 ; RUSSELL, 1969), but in many instances the implication that the lesion was due to a spider bite seemed unfounded. We have already noted that fleas, ticks, bedbugs, ants, biting flies and kissing bugs may produce lesions which can resemble a mild case of Loxosceles envenomation . The reader is referred to the excellent review by HiGnox (1968) for a description and excellent photographs on some of these entities. In consultation we have seen infected flea bites in several persons of considerable means, who were sent to us as possible `Loxosceles reclusa bites' . The social implications of the diagnosis of flea or bedbug bite can be understood . In other cases the patient has presented a history so similar in detail to the popular news accounts for L. reclusa bites that suspicion must certainly be entertained . This seems even more suspicious when legal problems become involved . We would like to emphasize a previous consideration, that unless the offending spider is identified we feel that a diagnosis based upon the lesion alone is very hazardous, and may not only confuse the diagnosis and result in unwarranted medical or surgical treatment but may delay the search for the real culprit, ifindeed it is an arthropod. We would like to point out that before (and even since) Loxosceles sp . were implicated in necrotic arachnidism, these bites were usually attributed to `bugs', `small snakes', ants, allergic reactions to fleas and other arthropods, and even to rats. In South America, where Loxosceles envenomation was reported by MACHtAVfiLIA, 1937, the bites were previously attributed to snakes, black widows, mice, rats, scorpions, tarantulas, lycocids and a variety of other animals (personal communication, D. R. Rodriquez, July 5, 1963). We feel, therefore, that before implicating a definite spider, some substantial evidence ofthe animal's involvement must be presented. As L. unicolor and L. arizonica can now be identified with definite lesions, some attention should be given to the reports implicating L. reclusa in Southern California. Since the appearance of the article by LEW1S and R>~AN (1966), 15 physicians and 33 non-medical persons in Southern California have called us to report bites by `Loxosceles reclusa' . In no case was the offending arthropod caught . In subsequent interviews with 16 ofthe persons concerned, only four had seen a `bug of some sort' on their person at the suspected time ofthe injury . Two ofthe 16 became patients at the Medical Center, and later identified the offending arthropod as the pajaroello tick, Ornithodros coriaceus, an arthropod long known for its biting habits and the lesion it produces . The other two persons were unable to identify the arthropod they had seen. A careful search of the homes or areas where the suspected bites were thought to have occurred was made in 14 instances. In no case was a Loxosceles species found. Some 24 other species of spiders were caught which is not a large number considering that at least 9 of the suspected bites were thought to have occurred in or near nurseries. It would appear to us that if L. reclusa was responsible for any or all of the bites with which it has been implicated, someone would capture one of these spiders and bring it to a physician or public health official . It should be noted that there are many araeneologists

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FINDLAY

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RUSSELL, WILLIAM G. WALDRON and MINGO B . MADEN

in Southern California, and that these people have collected thousands of spiders over many years. There are `spider clubs' which are out almost weekly, and scores of school children who bring spiders to their teachers for identification, and many of these are forwarded to us. It would seem that after 50 years of spider collecting in Southern California ifL. reclusa was responsible for necrotic arachnidism in the area, more than one specimen would have been found (WALDRON and Russei,L, 196 . This one specimen was found in a wood pile near a garage where the personal belongings of a family from the midwest had been stored . As the authors note in this paper, the `rare case of necrotic arachnidism seen in this area may sometimes be due to an introduced Loxosceles species, or to L. unicolor, which while endemic is apparently uncommon' . Those cases where Loxosceles is not involved, and where necrosis is a definite sequela, may be due to one or several other genera ofspiders. TREATMENT When we first suspected a Lozosceles species as being involved in necrotic arachnidism in Southern California (1959), one of us wrote Dr. W. J. Gertsch at the American Museum of Natural History in New York and inquired as to whether or not L. unicolor could be involved. While Dr. Gertsch stated he had not heard of a case of poisoning by this spider, he did not exclude the possibility that this species could inflict a wound. He also called our attention to certain works in the South American literature, and on the basis of these we developed our therapeutic program. As noted in our cases, we have tried excising the lesion, administering corticosteroids and metronidazole, and the local application of fibrinolysin and desoxyribonuclease to the lesion. However, since the chemistry of the venom is not known, nor the physiopathology, and adequate clinical experiences are lacking, no single therapeutic measure has been generally accepted. In our studies on the chemistry of L. unicolor venom we have not found any cytolytic fractions) present in sufficient quantities to account for the tissue necrosis . It would appear that the tissue changes are due to some autopharmacologic response to the venom, rather than to the direct effect ofthe poison. We agree with FAxnox et al. (196 that excision of the involved tissues may be the wisest procedure to prevent cutaneous necrosis caused by the venom. While the controversy over the value of corticosteroids in these cases is still very much in evidence, our own experience would seem to indicate that if started early they may abort the development of the lesion and the systemic effects. This is consistent with the findings by DII.LAxA et al. (1964) . In cases ofslow wound healing following rattlesnake venom poisoning, metronidazole has been found to be of some value (Russsi.L, 1966) and further therapeutic trial in Loxoscelesvenompoisoning seems indicated . Recently, one ofus has usedElase®fibrinolysin and desoxyribonuclease, combined (bovine), in several exudative lesions of snake venom poisoning with excellent results . In Case 4 the healing was rapid following its application to the wound . Also, in several lesions produced by unknown arthropods the use of Elase® has enhanced healing. REFERENCES

Dtr r .~r~ , C. J., Juvs~, G. T., HONSYCUTT, M . and HAYn$rr, C. R (1964) North American loxoscelism . Necrotic bite of the brown recluse spider. J. Am. med. Ass.188, 33 . Fwxnort, D . W., Wnvco, C . W., ROHIIVSON, D. W. and Mesreas,F. W . (1967) . The ttratment of brown spider bite. Plastic reconstr. Surg. 40, 482 . GExTSCx, W. J. (1958) The spider genus Laxoseeles in North America, Central America and the West Indies. Am. Mus. Novtt . 1907, 1 . Hianox, R . S . (1968) Common insect, mite and parasite problems inthe United States. Gen. Prac. 37, 84 .

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Jas, J. A., S~~ ena, W. A., Aosiua, O. M. and T~eRU.L, B. S. (1961) Reactions following suspoctod spider bite . A form of loxoscelism? Am.1. Dia. C1dld.102, 395. Lcwas, M. I, and R$a~uv, J. F.(19C~Necrotic arachnidism . Cal{J: Mcd.105,457. I~Gccfnevsr w, A. (1937) La Loxoscelea Iseta causa del aracnoidismo cutanoo o maacha gaagrenosa, de Chile. Revta. chi!. Hist. trot. 41, 11 . Rus.~,, F. E. (19C~ Metmnidazok in snaky venom poisoning. Memr. Inat . Brrtantan Slurp. Internac. 33, 845. Ru sser.c., F. E. (1%9) Spider bites. In : Crarent Therapy (CoNrt, H. F., Ed.). Philadelphia : Saunders . RussBa,, F. E. and Wninxorr, W. (1967) Spider bites, tick bites, Calf: Med.106, ?A8. W~,r~xox, W. d. (1968) Bite by the spider 77riodlna sylvana in Southern California. Toxlcon, 6, 71 . Wnr nnox, W. and RUS.4E[,L, F. E. (1%7)Loxosceles rechrsa in Southern California. Toxlcon, S, 37 . Note addedIn prooj.~ Since preparation of this paper a large colony of Loxosceles !seta has been discovered in Sierra Madre, California . The colony appeals to be conßnod to as area of several blocks. No bites by this spider have ban reported by physicians in the area. It is not known at this time how this species was brought into California from SouthAmerica, nor how long it hasbeen in the area. A study of the spider in this locale by the authors, Lowrie, and Thompson, has been initiated.