Chapter One – Nah-uh (Pittsburghese for “No way”)
It may come as a relief to our locals in Western PA that recluse spiders (Loxosceles genus) are rarely found here. We are too far north of their natural range. Within the recluse spider’s natural range, which is mostly the southern midwest, they are commonly found in homes. A six month study done in a Kansas home in 2002 revealed over two-thousand recluse spiders cohabiting with a family and there were no envenomations reported. With this, and other similar studies in mind, it’s no wonder that I’m highly skeptical when I hear a recluse bite story from someone living in Pittsburgh. With some questioning, these stories turn out to be inconclusive; they never actually saw the spider or their doctor made an assumption and labelled it as a “spider bite”. Here, I have to choose my battles when it comes to spider advocacy because some people hold their “bite” story as a badge of survival and it’s hard to convince them otherwise. I’m not saying it isn’t possible. I’m just sayin’ it’s highly unlikely.
When I’m doing spider presentations, venom is definitely one of the most popular talking points. Spiders are scary, they BITE, and aren’t they venomous?? This is usually when a recluse bite story is shared. What’s interesting is that most people around here have never seen a recluse spider in person. Any brown spider is suspect. To briefly answer the above hypothetical questions, “scary” depends on the spider knowledge of the beholder, spider bites are rare in general, and all spiders except for the Uloboridae family are venomous.
Recluse spiders (and widows) get all the attention because their venom happens to be medically significant. Out of the forty thousand kinds of spiders in the world, only a small fraction of spiders are dangerous to humans. There is potential for a recluse bite to be serious, but 90% of verified recluse bites result in swelling, redness, and pain with no damage to the skin and heal on their own without medical attention (Vetter, 2015).
Media hypes up fears and freaks everyone out with graphic photos that send the message that spiders are sneaky, strategic, and hunting you, your kids, and your pets! Some think that one bite from these spiders results in immediate “death skin” sores that eat holes in your body. In reality, serious cases of dermatological damage that result from a brown recluse bite are rare!
Lou Coticchio, (Florida Brown Recluse Project) from the University of South Florida, has recently done some very interesting recluse bite experiments. He conducted tests to see what it takes to make a recluse spider resort to biting. Lou used a gel that mimicked human skin and, without killing the spiders, he poked, pulled, squished, and yanked the spiders while they were pressed against the gel. His results showed that it really takes a LOT to make a recluse bite. Only under extreme duress were the most bites recorded. A real life example of extreme duress would be a spider pinned between clothing and a leg then being rolled and further pressed by fingers from scratching or swatting. Even after all of that, if bitten, ninety percent of recluse bites turn out to be nothing to worry about according to the literature on recluse bites.
Chapter Two – Git Aht (Pittsburghese for “Really??”)
So it came as quite a surprise when I actually got word that there was a population of brown recluse spiders in Pittsburgh. In 2016, a friend contacted me saying they were in her garage. She presented proof – a dead male recluse. This experience was MY first time seeing a recluse in person.
I had read enough on recluses to confidently identify the specimen to the genus level (Loxosceles). He was leggy and beige with no markings. There were no bands on the legs, no spots or stripes on the body, and no spines. There were six eyes in three diads. Lastly, there was the violin shape on the head, but let me warn you – the violin shape on the head can be, and has been, an unreliable diagnostic because people can conjure up seeing this shape on any spider if they want to. It was definitely Loxosceles, but I wasn’t sure which species. There are actually eleven native recluse species in the US: the Desert recluse (Loxosceles deserta), the Big Bend recluse (Loxosceles blanda), the Brown recluse (Loxosceles reclusa), the Grand Canyon recluse (Loxosceles kaiba), etc. For the full list, check out Bugguide.
I contacted Dr. Richard Vetter who is the authority on recluse spiders. He replied and confirmed that I did, in fact, have Loxosceles reclusa, the brown recluse. He said isolated populations of brown recluse spiders have been found outside of their natural range, but they remain isolated and do not disperse far. For my Burgh people reading this…there is no invasion here! This was a very rare (and to me, intriguing) find!
Chapter Three – Being nebby (Pittsburghese for “being nosy”)
It came without hesitation for me to investigate the location of where this recluse was found: a detached, unheated, two car garage in the South Hills. Talking to my friend, she said she hadn’t found any in the adjacent house, just in the garage, confirming that they really don’t go far. Armed with leather gloves, a thin rod for prying, and a flashlight, I found at least seven live recluses in different developmental stages, about a dozen discarded molts, and a few egg sac remnants, all signs that there was a breeding population. It was assumed that the spiders had been established by previous owners who may have moved there from recluse-native areas. The various furniture and flattened boxes that were left in the garage provided good hide spots. That, along with the unfortunate discovery of termites as a food source could be why the introduced spiders were able to survive.
That day, I collected two mature female recluses and two immature recluses. One of the mature females was gravid and produced an egg sac. Before long, I was a recluse nanny – the best way to really get to know first-hand how these spiders behave, grow, eat, move, mate, die, etc.
Chapter Four – Yinzer Recluses (Pittsburghese for recluses born in Pittsburgh)
Some of the things I learned about these infamous spiders is that they are not aggressive, even when guarding egg sacs. As you can see by the photos, I was fairly intrusive. On all disturbance occasions, the spider’s response was to run away.
They line their hide spot with cottony, thick silk, but don’t spin an artistic web of any form. It’s like a tangle. They can move very quickly, but only do so in spurts. They attack prey by biting and then backing off, biting and backing off (check out this video to see one attacking a fly). They can live a really long time in captivity compared to other spiders. More about longevity later…
A recluse egg sac averages about fifty eggs. I’m not really sure how many I had. The spiderlings cohabited in the original container with mom for awhile because I hadn’t figured out how to easily separate them. A bit of cannibalism and competition ensued even though I fed them squash bug nymphs and fruit flies. Not every spider got food so some spiderlings were larger than others. I eventually separated the remaining spiderlings into their own vials and ended up with twenty four of them creatively named #1 – #24.
Recluse spiders grow and molt (shed their skin) seven to eight times before they are full grown and able to reproduce. These stages of development are referred to as “instars” and a spider can be in any given instar for a few months before it molts again. A number of factors can affect how fast a spider grows: temperature, food availability, whether it’s captive or in the wild, etc. After the final molt, spiders reproduce, and then eventually die. Mom recluse lived another year after this egg sac and actually produced another the following summer. I don’t even now if the eggs from that second sac were fertile because I put it in the freezer. I thought raising twenty four recluse spiderlings was enough. Mom recluse died a month after the second sac.
I observed, took notes, and started to get individually acquainted with my orphaned Yinzer recluses. Some molted faster than others and their sizes varied. #12 was really big and #23 was always the smallest, even though they had the same number of molts. #15 got stuck during a molt and I was able to free it out of its old exuvium (shed exoskeleton) but not without having to sacrifice two legs. #17 got stuck in its fourth molt and didn’t make it. Many travelled with me to spider tabling events where I tried my best to debunk myths and misconceptions about them. It was impactful because folks could SEE a live recluse which was a first for many. As time went on, the spiderlings died off one by one. By March of 2020, only #19 and #21 were left and I was getting worried that my Yinzer recluses would die out completely. I should’ve saved that second egg sac!
But, as luck would have it, #19 had its final molt and I could tell by the swollen palps, it was a male. And #21 was a female! I wasn’t sure if it would work out since the spiders were siblings, but maybe they would mate and I could get another generation! I put them together in the same container and waited and waited for MONTHS and nothing happened. The two spiders seemed to ignore each other. Every time I checked, they would boringly be chillin’ on opposite sides of the cardboard. Was it because they were siblings? Do spiders even care about that?
Then I figured out why…the female, #21, wasn’t even mature! She had NOT had her final molt like I thought which meant she didn’t even have the internal plumbing to mate until now. I had miscounted her instars when I put the two spiders together. How did I know? I found the shed exuvium in the enclosure and she was slightly larger. I was surprised by this last molt! I looked back at my notes and was shocked to see how LONG it took her to mature! The average life span of captive-raised, female recluse spiders is a little over two years, but there are outliers. The literature notes a female living over five years! Mine is definitely an outlier. She emerged from the egg sac in 2016 and her final molt was in September 2020. It took her four years to mature! That’s crazy slow! And she’s still alive as of this writing.
Chapter Five – Redd up! Company is coming! (Pittsburghese for clean up the clutter, visitors are coming!)
#19 and #21 remained housed together through winter of 2021. I found #19 (the male) dead in May of 2021. He lived a long time, too, at almost five years old. I was sad that I didn’t see the two mate and wondered, again, if I had lost my unique recluse collection. However, two weeks later, I discovered an EGG SAC! Amid the white tanglings of fuzzy silk there was a mound of heavier layers with #21 resting next to it. This was promising, but spiders will produce infertile egg sacs. I checked the enclosure every day. #21 would sit next to the sac and tolerate my prodding forceps from time to time. Finally, in June 2021, the spiderlings emerged! I was so excited! Only my closest friends were able to appreciate how awesome it was. I mean, I know it sounds really funny to be so thrilled about recluse spiderlings!
I collected thirty-two spiderlings from mom’s enclosure and transferred them into their own vials. Two more egg sacs were produced, each with less babies and I kept ALL of them. The second egg sac revealed twenty-nine spiderlings and the third sac was only ten. It is typical for spiders to produce more than one egg sac from one mating. It’s also typical that the number of eggs decline with each succeeding egg sac. I am now the grand-nanny of seventy-one Yinzer recluses.
I’m hoping to rear this second generation to maturity and keep it going. I question the fitness consequences of inbreeding and wonder about the original recluse settlers in that South Hills garage…how many were there initially and how inbred is this population already? Does it even matter? After reading the paper from Aviles and Bukowski (in resource list below), I wonder if inbreeding would be a contributing factor to the long maturity time in addition to all of the other life history variables.
Chapter Six – Taking it dahn a notch (Pittsburghese for “calming down”)
The take aways from this post are that brown recluse spiders get way more notoriety than they deserve. Finding recluse spiders outside of their range is rare and isolated and does not suggest an invasion. These spiders are not aggressive. They can live a very long time. The “WOW” moments for me were, of course, finding a brown recluse population in Pittsburgh and realizing how long it took #19 and #21 to mature.
I recently followed up with my friend who owns the property where the Pittsburgh population was found. She reported that since getting rid of the termites and the boxes, she hasn’t seen any. They could have died out or just got better at hiding. In the meantime, I look forward to raising the third “Yinzer” generation for personal curiosity and educational outreach opportunities. I’m sure the conversations that result will start something like this:
“So THAT’S a brown recluse?? My aunt got bit by one of those!”
“Nah-ah! Where does she live?”
“East Pittsburgh, over by where the Animal Rescue League used to be.”
Avilés, L., & Bukowski, T. C. (2006). Group living and inbreeding depression in a subsocial spider. Proceedings. Biological sciences, 273(1583), 157–163.
Bradley, Richard. Common Spiders of North America. Berkeley, CA: University of California Press; 2013.
Vetter, Richard S. (2008). Spiders of the genus Loxosceles (Araneae, Sicariidae): a review of biological, medical, and psychological aspects regarding envenomations. Journal of Arachnology. Vol. 36; p. 150 – 163.
Vetter, Richard S. The Brown Recluse Spider. Ithaca, New York: Cornell University Press; 2015.
Vetter, Richard S. and Barger, Diane K. (2002). An Infestation of 2,055 Brown Recluse Spiders (Araneae: Sicariidae) and No Envenomations in a Kansas Home: Implications for Bite Diagnoses in Nonendemic Areas. Journal of Medical Entomology, Volume 39, Issue 6, 948–951.
Vetter, Richard S. Causes of Necrotic Wounds other than Brown Recluse Spider Bites. UC Riverside, Department of Entomology, Spider Research. https://spiders.ucr.edu/causes-necrotic-wounds-other-brs-bites. Accessed January 11, 2021.
Jacobs, Steve. Brown Recluse Spiders: Eleven species of Loxosceles are indigenous to the continental United States, four of which are known to be harmful to humans. Penn State Extension. https://extension.psu.edu/brown-recluse-spiders#:~:text=Outside%20their%20native%20range%20(which,therefore%20extremely%20rare%20and%20localized. Updated Dec. 11, 2008. Accessed Jan 13, 2021.
Sandidge, James S and Hopwood, Jennifer L. (2005). Brown recluse spiders: A review of biology, life history and pest management. Transactions of the Kansas Academy of Science. Vol. 108, no. 3/4
Ubick, D., Paquin, P., Cushing, P.E. and Roth, V. (eds). 2017. Spiders of North America: an identification manual, 2nd Edition. American Arachnological Society, Keene, New Hampshire, USA.