This poster created by a pest control company claims to show dangerous American spiders. It is full of bad information. Half of the species on this chart don’t even occur in the USA. Please, don’t share it anymore!
Please don’t rely on this chart for meaningful information about American spiders. This chart is the result of a clever company re-purposing something they put together for Australia. Seriously; the Australian spider chart is exactly the same! And, frankly, the info isn’t all that accurate for Australians, either.
This post will address the parts of this poster that are wrong (pretty much all of it), and then suggest some resources for accurate information about American spiders.
Info that is completely wrong on the poster:
- Mouse spider: does not occur in the US. Mouse spiders are not aggressive, and often “dry bite” when disturbed. In other words, most of the time they don’t even inject venom!
- Black House Spider: does not occur in the US. Also, known to be timid and not dangerous.
- St. Andrew’s Cross Spider: Does not occur in the US. Harmless.
Info that is mostly wrong on the poster:
- Hobo spider: the species pictured does not occur in the US. We have some spiders called hobo spiders, but they are not the same species as the Australian one with a scary bite. Introduced hobo spiders in the US don’t seem to have venom as toxic as the rumors. In fact, a recent study of the introduced hobo species found they were fairly harmless.
- Brown Recluse: This is actually a complex of up to 6 different species of spider, and they do not occur in all areas of the US. There is a complex mythology about the bite of the brown recluse. Research suggests that the bite, while not pleasant, is not a pathway to nasty necrosis. A lot of other things cause necrosis of the skin, which is often blamed on a hapless spider.
- Wolf spiders: Lots of wolf spiders occur in the US, but they are of minimal medical importance. No serious medical consequences of a wolf spider bite has been reported, and their bite is not painful or toxic.
Information that is slightly right on the poster:
- Garden orb-weaving spiders do occur in the US, and are beneficial and harmless.
- Huntsman spiders: the species in the photo does not occur in the US. We have some huntsman spiders, but they are much more modestly sized than the Australian and tropical versions. Harmless unless provoked, and even then pretty harmless.
- Trap Door spiders do occur in the US, although not the species pictured. They are harmless and fascinating!
- Black Widow Spiders do have a toxic bite, and do occur in the US, but that’s about as far as the correctness goes. There are 5 different Widow species in the US, and Black Widow bites are not lethal to humans. In fact, as of 2011, there are no known reported deaths from black widow bites in the US. Black widow spider bites can cause muscle cramping and abdominal pain in some people; pregnant women and children are most at risk.
To sum up: This poster is unhelpful and mostly filled with bullshit with regards to US spiders. Don’t rely on it, and don’t share it.
How can you know what information online about spiders is good information?
Easy! Go to your local Extension website. In the United States, every single state has an Extension service (or did until state budget cuts a few years ago, anyway).
“Each U.S. state and territory has a state office at its land-grant university and a network of local or regional offices. These offices are staffed by one or more experts who provide useful, practical, and research-based information to agricultural producers, small business owners, youth, consumers, and others in communities of all sizes.”
The Extension Service is charged by the USDA and each state government with producing factual, well-researched information for consumer use. You can tell you are on an Extension website because it will be affiliated with a land-grant university, and have a .edu web address. So, for example, searching for “Nebraska fact sheet spiders” gives me this information specific to that state (and also some tips about keeping a wolf spider as a pet!).
There are amazing, free resources available to you. Use them! And look for that .edu web address. Don’t listen to stories of a friend who knows a friend who lost their Aunt Gertie to a giant toxic banana spider that was in a pack of underpants. Seek out reliable information.
Some actual helpful, authoritative resources about American spiders:
- Spiders do not bite. Some common sense about spiders from an expert. A Must Read!
- Real, peer-reviewed info about American Spiders
- Common spiders of the East Coast
- Seriously, you weren’t bitten by a brown recluse
- How to identify a Hobo spider (PDF)
- Sac spiders don’t really make webs in your scrotum.
A personal note:
I just finished a move across country. As part of this move, I had to clean out the space behind my washing machine. I was hunkered over shelves, trying to wipe things off, and when I stood up I’m fairly sure that my entire head was covered in cobwebs. I…may have let out a sound of a frequency last produced by Little Richard hitting one of his high notes.
I mention this to let you know that even bug people get the heebie jeebies around spiders sometimes. It’s ok to not like spiders as long as you remember the vast majority of spiders are your friends. You don’t have to kill them! They are valuable (and free!) pest control for your yard and garden. Unless there is something seriously wrong with your personal hygiene, spiders have no interest in living on you or in you. Try to live and let live.
Yes, to all of this! Some of the most headbanging questions I get explained by attendees at the Entomological Society Meeting last month.
In the news recently: Operation Rat Drop, where tylenol-laden mice were dropped from planes over Guam. It’s not a bizarre headache remedy; the idea is to try to kill brown tree snakes (a non-native invasive species) when they eat the mice. Acetaminophen kills snakes. Who knew?
That reminded me of a similar–but much odder–project: Operation Cat Drop. It’s an oft-told story about DDT and unintended consequences. I was excited to see it had recently been covered in a journal!
In 1955, a malaria outbreak in Borneo was fought by spraying DDT and other pesticides. Several unintended consequences were observed after the sprays, but time and distance have muddled them quite a bit. The basic claim is that local cats died after the sprays, and this caused an explosion of rat populations, which lead to increased human disease. The RAF then (in the more exciting versions of the story) parachuted in 14,000 cats to remote Borneo.
Some things are known and documented; one unintended consequence that did occur post-spray was that caterpillars eating the roof thatch of homes increased 50%, with associated roof damage:
”The WHO team sent to investigate determined that moth larvae (caterpillars) living in the thatch were able to distinguish the presence of DDT and so avoided eating thatch sprayed with the chemical, whereas their parasites, small chalcid wasps that injected their larvae into the caterpillars, were highly susceptible to DDT, causing their decline and the subsequent increase in caterpillar.”
This is a fairly classic pattern, where pesticides disproportiately affect natural enemies, or living organisms that act as natural brakes on pest insect populations.
It is also known that cats did often die after DDT sprays, and this was observed in several different countries on different occasions, including in Borneo. It would make sense that cats would eat rats and insects (and, in some versions, geckos) affected by the sprays, and the pesticide would biomagnify in their kitty bodies. That, however, does not appear to be the case; cats’ habit of grooming themselves and ingesting residue of the pesticide was what allowed them to receive a lethal dose.
Which leaves us with the parachuting cats. There was a rat problem in the area, and there is a record of 20 cats being dropped in Borneo by the British RAF, along with some chickens, by parachute. But that’s it. They weren’t in little harnesses; they were in special containers that would cushion the drop.
It’s a fascinating story of how something basic took on a life of it’s own. The paper I’ve cited below suggests that some of the story’s inflation in kitty numbers can be attributed to an expatriate Brit with a big ego that initially started the rumors. I don’t have access to his original document, which included little drawings of cats in individual parachutes, so I have done my best to recreate them here.
From there, the story was reproduced and took on a life of it’s own–I’ve seen versions where all the cats landed in the sea and drowned, versions where there were 10,000 cats, and versions where high-velocity falling cats killed people when they fell on them. All false, but far more interesting than reality.
Before anyone begins to trot out the usual “DDT will save us all” crap, I want you to read that paper and notice that it clearly lays out a whole sequence of unintended consequences from DDT sprays, including the problem of resistance from as early as in the 1950s. This paper is a reminder that we should not be uniformly pro- or anti-DDT; we should make pesticide decisions based on the best available, real evidence. Not propaganda.
O’Shaughnessy, P. (2008). PARACHUTING CATS AND CRUSHED EGGS The Controversy Over the Use of DDT to Control Malaria American Journal of Public Health, 98 (11), 1940-1948 DOI: 10.2105/AJPH.2007.122523
Since I talked about pioneering women earlier this week, how about examining the Entomological/Etymological connections of Grace Hopper?
I should give her the proper title–Rear Admiral Hopper. (A biography described her as “Admiral of the Cybersea.”) Hopper received a PhD in Mathematics from Yale University in 1934, which could not have been easy. She left a faculty position at Vassar to join the Navy in 1943 and was assigned to work on the “Mark I Electromechanical Computing Machine.” It was 51 feet long, 8 feet high, and 8 feet deep.
From there, she went on to work in academia, industry, and the military, staying on the cutting edge of computing. Her best known innovation is the compiler, but she is also responsible for COBOL, FORTRAN, and many other computing innovations.
Whether or not Hopper was the person that coined the term “computer bug” is a source of some controversy. The Navy seems to support the idea that it was Hopper that squashed the first computer bug; there is an actual photo of the offending insect on Hopper’s US Navy webpage:
Moth found trapped between points at Relay # 70, Panel F, of the Mark II Aiken Relay Calculator while it was being tested at Harvard University, 9 September 1947. The operators affixed the moth to the computer log, with the entry: “First actual case of bug being found”. They put out the word that they had “debugged” the machine, thus introducing the term “debugging a computer program”.
In 1988, the log, with the moth still taped by the entry, was in the Naval Surface Warfare Center Computer Museum at Dahlgren, Virginia.
Somehow, “computer moth” just doesn’t have the same resonance.
If you dig a little deeper, though, it appears the use of “bug” to describe a technical problem has a complex history–and in fact, may not have originated with Grace Hopper at all.
“The OED Supplement records sense (4b) of the noun bug (“a defect or fault in a machine, plan, or the like”) as early as 1889. In that year the Pall Mall Gazette reported (11 Mar: 1) that ‘Mr. Edison … had been up the two previous nights discovering a ‘bug’ in his phonograph–an expression for solving a difficulty, and implying that some imaginary insect has secreted itself inside and is causing all the trouble.’….
This meaning was common enough by 1934 to be recognized in Webster’s New International Dictionary: ‘bug, n…. 3. A defect in apparatus or its operation… Slang, U.S.’” (citation)
So, the “actual bug” notation in the lab notebook above probably reflects the amusement of the technician at finding a physical bug, when the word bug was already in use as slang for a problem.
It does appear that the term “debugging” came into use around that time period, but I haven’t seen any evidence firmly tying it to this particular moth. Oh well.
BTW, The Grace Hopper Celebration of Women in Computing is the largest technical conference for women in computing. The deadline to apply for scholarships to attend the conference is May 31, 2011. Go and find some new computer bugs!