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Children's Health & Safety Association

Issue 43: July 2018

Monday, 30 June 2014 12:06

Large Spiders of Ontario

Written by 

spiders-001June 30, 2014 – Humans may be comfortable with creatures that have two legs or four legs, but as a rule we’re somewhat squeamish or downright frightened by those that have eight legs (like spiders) or none at all (like snakes). And the bigger they are, the worse it is!

I’ve been to the Amazon (pictured left), parts of Africa, the rain forests of Costa Rica, forested sections of Vietnam, and enjoyed hiking through the bush in search of interesting insects to photograph. Of course, I encountered giant insects in Malaysian and Thai cities too, but there’s something exciting about parting huge ferns, walking under monstrous trees, and carefully examining logs and tree trunks for camouflaged bugs and arachnids.

spiders-003


If questioned about large spiders, most of us would likely think of tarantulas – and we’d issue a sigh of relief knowing they live in places like South America, the Far East, Australia, the Middle East, Africa and Mexico. Tarantulas, such as the one pictured here, have body lengths that typically range from 2.5 to 10 cm, and leg spans that extend from 8 to 30 cm.

As many cottagers know, we have our own share of large spiders in Ontario. My house is located on a lake near Algonquin National Park in northern Ontario, and two of our largest spiders, the wolf spider and dock spider, are resident here. They do not come close to the monstrous sizes of tarantulas, but they are impressive when compared to their other Canadian relatives. There is no need for us to fear them, however.

Wolf Spiders

Wolf spiders have eight eyes arranged in three rows. The bottom row consists of four small eyes, the middle row has two very large eyes and the top row has two medium-sized eyes.

Wolf spiders belong to the family Lycosidae, from the Ancient Greekword "λύκος" meaning "wolf". They are robust and agile hunters with excellent eyesight. For the most part, they live solitary lives and hunt alone. Unlike most spiders that spin webs to entangle other insects, they are ground-dwellers that pounce upon their prey and even chase it over short distances.

Because they require good vision for hunting, their eyes, located on the front of their heads, are forward facing. Wolf spiders have eight eyes arranged in three rows. The bottom row consists of four small eyes, the middle row has two very large eyes and the top row has two medium-sized eyes. The backs of their eyes have a reflective membrane called a tapetum that aids in night vision. You can locate the wolf spider at night using a flashlight because the light reflected from their eyes will make their presence known.

spiders-007www.everythingabout.net states, “The hunting strategies of wolf spiders are perhaps the most diverse of any spider group. Many are active, wandering hunters during the day in sunny areas along the ground and in vegetation; others hunt at night and remain in silk-lined retreats during the day. Still others live and hunt in aquatic environments, walking on the surface of ponds or on submerged vegetation. Some wolf spiders dig burrows in which they lie in wait for passing insects and other prey. Of the spiders that dig burrows, some add a moveable trap door at the burrow entrance while others build an elevated lookout point.”

Because wolf spiders depend on camouflage for protection and hunting, they do not have a flashy appearance like other spiders. In general, their colouring is appropriate to their favourite habitat. They have stout bodies (low to the ground) and long, thick legs. Fully-grown females are about 6 cm long; males are slightly smaller in size and darker in colour. The wolf spider pictured at left was living in my outhouse throughout late summer and early autumn, eating smaller spiders and various other insects that happened to wander in. It was a welcome guest – but I always made sure of its location before I sat down!

A wolf spider bite usually happens out of ignorance on the part of the human, and fear reaction on the part of the spider. When a wolf spider is afraid, startled or feels threatened, it will bite with no hesitation. A wolf spider bite is no doubt painful and might even be a traumatic experience for any individual; however, a wolf spider bite looks much scarier than it really is, just like the spider that caused it.

The following chart is from www.spiderbites.net (also listed in the “References” section):

Wolf Spider Bite Appearance

Wolf Spider Bite Symptoms

Wolf Spider Bite Toxicity

Wolf Spider Bite Additional Information

After being bitten, fang marks and tearing of the skin might be present, particularly if a large wolf spider is the culprit. Oftentimes though, there is simply redness and swelling in the area though some cases which are disputed claims to have developed skin lesions as well.

The number one sign of being bitten by a wolf spider is generally the pain that comes with it. The pain may last for up to 10 days together with swelling in the area of the bite as well as swelling of the lymph glands. In some cases, the skin around the area of the bite may darken in colour.

A bite from a wolf spider is venomous but is not considered to be fatal. They are not like the spider bites from the dangerous black widow, hobo, and brown recluse spider in terms of the damage and harm it presents to humans.

In some severe cases, the bite can develop infection and this can lead to complications. To prevent this from occurring, proper care and treatment of wolf spider bites must be implemented.

spiders-008Wolf spiders are unique in the way that they carry their eggs. The egg sac, a round silken globe, is attached to the spinnerets at the end of the abdomen, allowing the spider to carry her unborn young for a period of two to three weeks. The abdomen is held in a raised position to keep the egg case from dragging on the ground. Despite this handicap they are still capable of hunting. When the spiderlings are ready to hatch, the mother tears a hole in the sac. Upon emerging, the young clamber up their mother's legs and crowd onto her abdomen. The female carries them on her back (see photo) for a week or so before they disperse.

Dock Spiders

Dock spiders belong to the family Pisauridae, which are closely related to wolf spiders.  They are the largest native spider species in Canada. Other common names for these spiders include fishing spiders and wharf spiders.

At one time it was believed that the females killed and ate the males after mating, similar to the behaviour of black widow spiders, but the dock spider male actually dies after expelling its pedilaps.  

Two species, Dolomedes tenebrosus and Dolomedes scriptus are common dock spiders.  Both species are brownish-grey in colour, with black and light brown markings (‘chevrons’) on their abdomen. The body length of mature females can easily exceed 2 cm, and when the legs are included lengths of 9 – 10 cm are typical. Males are much smaller - half this size or less. Two of the references at the end of this article include videos of dock spiders mating. At one time it was believed that the females killed and ate the males after mating, similar to the behaviour of black widow spiders, but the dock spider male actually dies after expelling its pedilaps. The female may snack on his withered body afterwards, but she isn’t his killer.

As mentioned previously, wolf spiders attach their egg sacs to the end of their abdomen. A Pisaurid female, however, holds the egg sac with her fangs and carries it underneath her body.  When the eggs are ready to hatch, the female builds a silken, tent-like ‘nursery’ typically spun in and among grasses, low-growing vegetation, between rocks around the margins of water, or under the wooden planks of a dock. Upon hatching, the young spiders live in this protected environment for the early stage of their lives. Because of this behaviour, Pisaurids are commonly known as nursery-web spiders.

spiders-011The bodies and legs of Dolomedes spiders are covered with short, velvety hydrophobic (repel water) hairs. Using the surface tension of water, they are able to stand on or run on the tops of ponds or lakes. They can also dive beneath the water’s surface after trapping air bubbles within their body hairs. All spiders breathe with book lungs, located beneath their abdomens. Dock spiders open their lungs into the air film when submerged, allowing underwater breathing – like a scuba diver. The trapped air bubbles make them very buoyant, so they quickly pop back up to the surface unless they grab hold of a stone or plant under water.

Like wolf spiders, they do not spin webs for the purpose of snagging their victims. They hunt their prey. Dolomedes species tend to be robust with thickset legs that allow them to tackle prey larger than themselves. Hunting is usually done at night. Good eyesight would normally be required when there is little or no light, but the dock spider primarily depends on its ability to sense movement.

While holding onto the shore or the side of a dock with their back legs, they stretch their front legs out onto the water’s surface and patiently wait to sense the vibrations of approaching prey (they have a range of vibration-detecting organs, including very sensitive hairs on their legs and feet). They are able to discern the direction from which the vibrations emanate and the distance to the source. When they detect the ripples from prey, they run across the surface to subdue it using their foremost legs while injecting venom to kill it. They mainly eat insects, but some larger species are able to catch small minnows. Under normal circumstances they do not bite people. Just be careful where you step when walking on the dock in bare feet - getting ready for that dive into the cool water on a hot summer’s day!

We may shudder when we see these large spiders, but rest assured - the large spiders of Ontario are just as happy to avoid us. They mean no harm, they are not a danger to us, and we should leave them alone to catch other insects. We can happily enjoy our summers while they are left to enjoy theirs!

References

General Information on Spiders

spiders-014How Are Spiders Helpful to People and the Planet? – includes information about their diets, webs, bites and reproduction

Spider Information – comprehensive information from Spiderzrule

The Biggest and Largest Spiders of the World – photos, text and videos

Spider – Canadian Encyclopaedia

Spiders – this Government of Canada web site discusses wolf spiders, cellar spiders, house spiders, black widow spiders, and fishing spiders – and how to get rid of spiders from your home

House Spider Myths – are they a danger?

Spider Identification (Canada) – photos and comments

Spiders of Eastern Canada and USA – pictures and names of hundreds of spiders

Spider Photo Gallery – 28 photos and descriptions of spiders native to the Ojibway Nature Centre in Windsor, Ontario

Spiders of North America – 65 different spiders are listed and discussed, with photos

Spiders of North America – search by name

Spiders of North America – search by image

Spider Identification (USA) – pictures, toxicity, identification, habitat

Common Spiders In and Around Homes – excellent photos and descriptions including a comparison of the differences between spiders and insects

 

Wolf Spiders

Top Twenty Facts About Wolf Spiders

Everything About Wolf Spiders – habitat, appearance and hunting strategies

spiders-016

Wolf Spiders – extensive notes from Red Planet Inc.

Wolf Spiders – extensive notes from Bumblebee.org

Wolf Spiders – characteristics, habitat, diet, reproduction and venom

Wolf Spider Bites – identification, symptoms and treatmentspiders-017

 

Dock Spiders

Fishing Spider – good photos

Fishing Spider – description and life history

Facts About Dock Spiders – short notes and comments

Sittin’ on the Dock of the Bay – Canada’s largest spider

Dock Spider: Friend or Foe? – Great pictures and video of mating!

Mating of Fishing Spiders – death of the male (Video)

Dock Spiders Are Nothing to Fear – comments from Bow Narrows Camp

Dock Spider – photo on Muskoka cottage blog

Giant Dock Spiders in Muskoka – Video of dock spiders in cottage country, Ontario, Canada

Dock Spider – Video (humorous audio)

Wolf Spiders and Dock Spiders: A Comparison – extensive notes and photos

Read 163520 times Last modified on Wednesday, 18 April 2018 15:43

20 comments

  • Comment Link Rob Didur Saturday, 10 August 2019 03:22 posted by Rob Didur

    Great stuff, Dave... I have counted - and identified eight different spider species on my property.

    Good job, thanks again.

  • Comment Link Colton Wednesday, 10 July 2019 16:41 posted by Colton

    Technically speaking the southern part of Canada is sometimes referred to as northern Canada... Something to do with 1812. But anyways great post that calmed me down after I thought I saw a wolf Spider buy after reading I realized that it was not

  • Comment Link Steve Tuesday, 14 August 2018 11:54 posted by Steve

    Great article, one question though.... When did they move Algonquin Park to Northern Ontario? It's been in Southern Ontario my whole life. :)

  • Comment Link Rosamond Buchmeier Monday, 19 June 2017 11:11 posted by Rosamond Buchmeier

    Super blog post!

  • Comment Link JaimeCit Wednesday, 18 January 2017 10:06 posted by JaimeCit

    Good post! I read your blog often and you always post excellent content. I posted this article on Facebook and my followers like it. Thanks for writing this!

  • Comment Link Peter Wednesday, 13 July 2016 05:59 posted by Peter

    Good information about large spiders.

  • Comment Link Sherman Saturday, 12 March 2016 12:10 posted by Sherman

    Content on this website is genuinely awesome. Keep up the good work people.

  • Comment Link Efren Thursday, 26 November 2015 14:14 posted by Efren

    I am very inspired with your writing talent as well as the structure of this blog. It is rare to see a great blog like this one these days.

  • Comment Link Scott Monday, 02 November 2015 03:23 posted by Scott

    Excellent blog.

  • Comment Link Patricia parks Monday, 07 September 2015 17:28 posted by Patricia parks

    Can you help me identify a spider if I send you a picture?

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