Wolf spiders are on the hunt in NH and Maine: Nature News

As winter comes to an end, I’ve been noticing the rustling of life under and on top of the snow.  On warm days the snow fleas are busy hopping about on the surface of the snowpack feeding on algae and basking in the sun.  This past weekend, while on a Great Works Land Trust hike at Rocky Hills Preserve in South Berwick, our group found a large wolf spider in the middle of the trail.  It was in the high 40s, enough warmth to motivate this spider to come out and search for prey (most likely those hordes of snow fleas).

The spider we found was a type of wolf spider.  These spiders don’t spin webs to catch their prey.  Instead, like the eponymous wolf, they chase their prey down.  Unlike wolves they hunt alone.  These are typically large, fast, hairy spiders and are visual predators, relying on their eight eyes to track their prey.  Wolf spiders have excellent night vision and usually hunt at night. However, this time of year they need warmth to get out and be active so are likely to be found patrolling the snowpack on warm, sunny days.  Later in the year, during the summer, it is fun to go look for them at night–just like our local mammals, you can find wolf spiders by their eyeshine - tiny little pinpricks of light that show up in a flashlight’s beam.  

Contrary to popular belief, most of our native spiders don’t come inside during the winter.  They are adapted to this climate.  As the temperatures start to cool off in the fall, spiders start producing an ‘antifreeze’ in their tissues, a glycerol compound that prevents hemolymph (the invertebrate version of blood) from freezing and bursting.  But this isn’t enough to protect them from deep freezes, so they also seek out protected areas, under the snowpack and leaf litter.  There they will hunker down and go dormant for most of the deep cold of winter.  Their metabolism will slow and they’ll draw their legs up against their bodies to minimize water and heat loss.  They can stay like this for months but will emerge on warm days to hunt.   

This past weekend was a perfect time for them to be out hunting.  The air temperature was in the 40’s, probably even the 50’s when in full sun.  We found thousands of snow fleas, tiny primitive invertebrates, hopping around on the surface of the snow.  These aren’t fleas, they can’t bite you.  They are so named because of their peculiar method of locomotion, they hop, sometimes 1 or 2 inches.  However, unlike fleas who use their muscular hind legs to jump, snow fleas have a springing organ, the furcula, tucked under their abdomens that is like a lever or a spring held closed under high tension. When they need to escape danger, they release this lever-like appendage and are propelled in random directions into the air.  These are fairly tiny prey, so I like to picture the wolf spider as a real wolf, hunting hordes of mice or lemmings over the vast snowscape.  

There was a very cool study (pun intended) that came out in 2018 about how spiders (in this case Arctic wolf spiders) might help mitigate some of the effects of warming on decomposition.  Decomposition (breaking down dead organic material by fungi and bacteria) is good because it releases nutrients like nitrogen into the soil, fertilizers that help plants grow.  But, decomposition also releases potent greenhouse gasses - carbon dioxide and methane.  Warming increases decomposition, thereby increasing release of greenhouse gasses.  

The study, out of Washington University in St Louis (Talia Ogliore  July 23, 2018), found that wolf spiders in the Alaskan Arctic are so abundant they outweigh real wolves. Wow!! These wolf spiders love to eat snow fleas (aka springtails or Collembola).  Snow fleas eat decaying plants and fungus (a decomposer). “Arctic wolf spiders are thus said to have an “indirect” effect on decomposition. The spiders eat animals (springtails) that eat fungus; if more fungus-eaters get eaten, then fungus grows unchecked. When there is a lot more fungal activity, there is faster decomposition.”  That sounds bad–fewer snow fleas, more fungus, more decomposition and therefore more greenhouse gasses released. But the surprising result of this study was that as temperatures warmed in the Alaskan Arctic, these wolf spiders shifted their prey preference to other small invertebrates, leaving more snow fleas to eat the fungus, combatting the increase in decomposition, decreasing the release of greenhouse gasses from the warming Arctic. 

I haven’t heard of an equivalent study of wolf spiders down here, but see them frequently enough to know that they are common backyard spiders.  It looks like we will have snow for a bit longer.  But also, with the onset of spring, we will have warmer days.  So, I expect to find more and more spiders emerging from their winter dormancy, out hunting on the icy expanses of my backyard. 

Susan Pike, a researcher and an environmental sciences and biology teacher at Dover High School, welcomes your ideas for future column topics. Send your photos and observations to spike3116@gmail.com. Read more of her Nature News columns online at Seacoastonline.com and pikes-hikes.com, and follow her on Instagram @pikeshikes