The Unsettling Reason You Should Never Squash A Spider In Your Home

When it comes to seeing spiders in your house, your first reaction is likely to kill it as fast as you can (or jump out of your skin, but no judgement here). Such habits or instincts may not be advantageous in the long run, though. Many spider species help control other pest populations (which is reason enough why you shouldn't kill them), but squishing certain spiders could have horrifying results.

Black Pest Prevention president Nicole Carpenter told Tom's Guide, "Squashing a female may release dozens of baby spiders if she's carrying eggs." As seen in social media videos, smashing a pregnant or nurturing spider mother would look like your worst nightmare coming true if you have arachnophobia: tiny spiders running in all directions away from a flattened female spider corpse.

One of these videos grabbed worldwide attention in 2015. Danny Ford, the uploader who filmed his video of the scattering spiderlings in South Australia, told National Geographic, "We got a bit of a surprise when I squashed it with a broom as hundreds of baby spiders came crawling out of the mother." While it's possible for these babies to survive and turn into an infestation, McGill University arachnologist Christopher Buddle noted that the chances of survival aren't good after their mother dies. Still, who would want to take that risk?

There are only a few species of spiders that either carry their egg sacs or carry their newly hatched spiderlings on their backs, such as cellar spiders (daddy longlegs) and nursery web spiders. But the wolf spider, known for its unique parental behaviors, does both of these.

The process of caring for its young starts when the female wolf spider seeks an area that is covered and isolated where it can lay eggs after mating. Unlike other species, it doesn't just lay eggs, encase them in a silk sac, and hide them somewhere easy to guard. Rather, it carries the egg sac with its spinnerets — the conical, tubular organs that produce its silk. The wolf spider rips open the sac when it's time for the eggs to hatch, but the new spiderlings don't go on their merry way. Instead, the babies flock back to the female's body and legs, and she carries them around for a couple of weeks until they're able to fend for themselves.

Norman I. Platnick, a former arachnologist at the American Museum of Natural History, weighed in on the aforementioned 2015 YouTube video. He told National Geographic that "these spiderlings were on the mother, and did not crawl out of her." So, before going on the attack when you see a big spider in your house, it would be wise to be able to tell the difference between male and female wolf spiders in case it's a female carrying an egg sac or its spiderlings. The same goes for other species that carry their egg sacs with them.