Garden Helpers: Awesome Arachnids

Hobo Spider ( Eratigena agrestis )

Hobo Spider (Eratigena agrestis)

There are many people who have some level of arachnophobia, or a fear of spiders.  While most keep to themselves, there are some that are highly aggressive when disturbed.  Generally these species rely heavily on web cues and have rather poor eyesight.  The image of an elderly man, sitting on his porch with a rifle and shooting at anything that enters the yard comes to mind.  One example of these species is the Hobo Spider (Eratigena agrestis ).  As with most species, if they feel threatened, especially if the potential threat cannot be easily identified, an attack/defense instinct is largely the first point of call (4).  While these spiders have been thought to have necrotic venom and be highly dangerous since studies conducted in the late 1980s, new research has refuted that (5), and hobo spiders are no longer considered to be any more dangerous than others.  The only exceptions to this are in instances when someone has a pre-existing/underlying condition that causes atypical conditions in their particular bodily systems.   Keep in mind: while there are tens of thousands of arachnid species, not many are harmful to humans, though all have some level of toxin.  This is what allows a spider to paralyze its prey in order to feed. 

Be aware, dear readers, that spiders are natural hunters.  That is their ecological niche.  That is what they do, much like wolves and big cats in their respective environments.  When I say they have toxins, I mean that is their weapon.  Even the smallest of spiders can and do hunt for themselves.  In human terms a species' toxins are the equivalent of using poison-tipped arrows to bring down big game and/or enemies. 

It is also important to consider that while you may not be a fan of our eight-legged compatriots, without them in their many permutations, the insect population would be insanely high.  I'm not talking about the fun insects that everyone likes either: the butterflies, moths, dragonflies, and others.  Being that spiders fulfill an ancient ecological role, their presence is important to the sustainable whole.

Bold or White-Spotted Jumping Spider ( Phidippus audax )

Bold or White-Spotted Jumping Spider (Phidippus audax)

Some spiders, like the one on the right, do not build webs.  If I have identified the species correctly, this is a Bold or White-Spotted Jumping Spider (Phidippus audax), They can jump rather long distances and tend to move jerkily.  They are a sexually dimorphic species (either the male or female is smaller that the other).  In this case, the males are about half an inch long, while the females can be up to three-quarters of an inch.  At the time of photographing this spider,  It appeared slightly less than one inch long, so that is also in line with this information.  They tend to eat insects, caterpillars, and other spiders, only acting aggressively  towards humans when attacked.  Even then their bites very rarely have more impact than a slight sting (1).

Golden Huntsman Spider ( Olios giganteus ).

Golden Huntsman Spider (Olios giganteus).

Adult huntsman spiders, as their name suggests, also actively hunt prey, rather than building webs and waiting for something to spring their traps.  Here, we have an example of a Golden Huntsman Spider (Olios giganteus).  Due to their body morphology and appearance, they are also sometimes referred to as giant crab spiders.  At the time this photograph was taken, the spider was probably 5 inches across.  With the legs being flexed, the full foot-to-foot length would probably be more like 6 or so inches, making the legs about 2.5 inches each (the higher side of average size for females of this species).  They are rather docile and, like the Bold Jumping Spider, rarely bite humans, unless threatened.  Even so, unless you are experienced and trained with handling them, let them continue being their fabulous selves.  It's less potential trauma for both of you that way.  This is even more pronounced if you encounter a female, defending her spiderlings (spider young), or egg sac (2,3); she maintains an aggressive pose until the perceived threat disappears or until she feels the need to attack.    Their diets primarily consist of insects, other invertebrate creatures, and small skinks and geckos (3).  As our yard has an abundance of lizards, I would posit that they are likely on the menu too, though my research has not specifically stated such.  Huntsman spiders tend to hide in small spaces, able to squeeze into cracks and irregularities in bark in order to blend in and remain undisturbed.  While not exactly "gentle," per say, these spiders are relatively non-threatening.  Like most, if they are left to their own devices, all is well.  They might be large and have a somewhat fierce look about them (similar body morphology to both crabs and tarantulas will do that), but they're rather beneficial to the garden and provide natural pest control.  They're really rather beautiful.  

Take care of your fellow creatures and they will take care of you.  We're all part of a complex, interconnected whole.  Be well.

Till next time,

Katheryn


 

 

Sources:

1. Missouri Department of Conservation. https://nature.mdc.mo.gov/discover-nature/field-guide/bold-jumper

2. Geoffrey K. Isbister & David Hirst (2003). "A prospective study of definite bites by spiders of the family Sparassidae (huntsmen spiders) with identification to species level". Toxicon42 (2): 163–171. 

3. Filmer, Martin (1997). Southern African Spiders. City: BHB International / Struik.

4. Crawford, Rod (10 September 2010). "Myths about "Dangerous" Spiders". Burke Museum of Natural History & Culture.

5. "CDC - Venomous Spiders"The National Institute for Occupational Safety and Health (NIOSH). Retrieved 7 May 2017.