Most people don’t welcome spiders in their home, but once they get to know the bold jumping spider, they might change their minds. Don’t grab the nearest shoe to smash it, don’t be put off by its looks. Despite having eight fuzzy legs and large iridescent green fangs, this spider is a helpful, tidy housemate.
Bold jumping spiders are pretty big– their bodies are about a quarter to a half-inch long. And though they may look fierce, they are harmless to humans. According to Penn State entomologists, your chances of being bitten by one are “slim to none.” The rare accounts of jumping spider bites suggest the bite causes a reaction similar to a mosquito bite.
But if you are an insect, these spiders are the stuff of nightmares- a lion stalking you in tall grass, poised to pounce… Unlike many spiders that spin webs, sit back and wait for insects to fly into them, bold jumping spiders are active hunters. In fact, they don’t spin webs at all, which means they won’t leave dusty cobwebs in the corners of your home.
Jumping spiders hunt during the day in open areas, such as walls and windowsills, using their keen eyes to spot their prey. Unlike other types of spiders, they have excellent eyesight and an almost 360-degree field of vision. The bold jumping spider will pounce on any insect smaller than itself, including houseflies, mosquitos, small crickets and other uninvited guests in your home.
Once prey is spotted, jumping spiders sneak up within striking distance– which for a jumping spider is pretty far. They owe their astounding jumping ability to hydraulics, not solely muscle. These spiders are able to rapidly increase the internal fluid pressure in their legs, propelling themselves 10-50 times their body length and pouncing on their insect victims. US Track and Field athlete Mike Powell, who holds the world record in the long jump, can jump less than 5 times his body length– and that’s with a running start.
Though bold jumping spiders don’t construct webs, they do make spider silk. They use a single line of silk as a tether to catch them in case they make a bad jump, kind of like a rock climber’s rope or bungee jumping cord. The female bold jumper also uses her silk to make an egg sac and small “den” where she hides with the sac and then her spiderlings when they hatch.
Jumping spiders are fun to watch– scientists who study their behavior believe they are very “intelligent” given the size of their brains. Most jumping spiders perform courtship “dances.” A couple of years ago a video of a colorful dancing spider went “viral” on the internet. The species shown in the video was the Coastal peacock spider from Australia– a species of jumping spider, just like our very own bold jumper.
Like a good guard dog, the bold jumping spider defends your home from intruders, albeit very small ones. But unlike a dog, that sheds hair and tracks in dirt, jumping spiders don’t leave a mess. So next time a jumping spider has moves into your home, consider letting it stay. While it can’t be counted on to help out with the rent or mortgage, it may still earn its keep.
This article originally appeared in the Grand Junction Daily Sentinel in September 2016.