If the sight of a spider makes your heart race, you’re not alone. According to the American Psychiatric Association, about 40% of people who have one phobia or another are arachnophobic. And a British study involving 261 adults showed that nearly 32% of women and 18% of men reacted with fear or disgust to real spiders—and even to images of spiders.

But think about it. If you’re afraid of spiders and you live in a city and hate cockroaches, maybe you should think twice about your fear. Spiders eat cockroaches. And according to scientists from Sydney, Australia, city spiders are quickly evolving to become, well, roomier. This may sound scary, but it also probably means they’re getting hungrier and better at keeping the cockroach population down. The research arachnologists collected spiders from parks and gardens in the city of Sydney but also from the vast areas of Australia in which few people live and plants and animals run wild. They measured the size of every spider and recorded its weight. And they found that in cities the spiders were relatively huge. Why? The scientists speculated that it’s because cities tend to be warmer, as roads and buildings absorb sunlight and don’t let go of the heat as night falls. Or, hey. It might be because there are more cockroaches in cities, and so spiders don’t have to roam very far to find food.

Fun Facts about Spiders (Arachnophobes: Read with caution.)

1. Many people know that spiders have eight legs. But what isn’t as well-known is that most spiders have eight eyes circling their heads.
2. Spiders can see ultraviolet light.
3. Don’t waste time at Disneyland. There’s a Spider Pavillion at the Natural History Museum of Los Angeles County. Every fall, hundreds of free-roaming spiders from fifteen local and exotic species roam through the exhibit.
4. The fangs of the Australian Funnel-Web spider are so strong it can bite through a shoe. Which is too bad, because its venom can kill an adult human within an hour.
5. Spiders have taste buds on the tips of their legs, and they hate the taste of lemon oil. If you don’t want them helping you control your cockroach population, putting Lemon Pledge on your windowsills and doorframes might be a good idea.
6. It’s very tough to drown some spiders. Scientists in France found that a certain spider that lives in marshes can survive 36 hours completely submerged in seawater.
7. Spiders that prowl at night are usually dark so that their prey can’t see them. But scientists in Taiwan have discovered that many of them have bright stripes on their bellies, which they can use to attract insects like moths that fly toward light. When the researchers painted over the belly stripes, spiders caught far fewer moths.
8. A certain bird-eating tarantula in South America can grow to be a foot long, and has been known to snatch birds from their nests.
9. Pound for pound, the silk that spiders spin to create their webs is tougher than steel.
10. For centuries, humans have wanted to harvest spider silk for their own use. But the problem with creating and managing spider farms is that spiders tend to kill each other.
11. No wonder Little Miss Muffet was scared. Spiders may kill each other but they can’t chew each other. They don’t have teeth. Their mouths are like straws. They suck blood.
12. The real Little Miss Muffet? Her name was Patience, and her father, the Reverend Dr. Thomas Muffet (1553-1604), thought that having spiders roaming about the house could prevent or cure gout and allergies. That’s not a popular belief today. Still, certain spider venoms have been turned into medicines including pain killers and treatments for brain cancer and muscular dystrophy.

Spider Photo Credit: Pascal Gaudette (Doundounba on Flickr, CC BY-NC-SA 2.0)

Cockroach Photo Credit: Craig Stillcoe (On Flickr, CC BY-NC-SA 2.0)