Is a spider about to eat you?

A recent entomological survey has concluded that a worldwide abundance of spiders means that, theoretically, the eight-legged arachnids could eat all of the humans currently on the planet in the space of just 12 months. This conclusion is however, only to put the amount of food that spiders eat into a comparative perspective, as spiders mostly eat insects, not people.

The survey conducted on homes in North Carolina found that spiders were present in 100 percent of the homes that were examined, which included 68 percent of bathrooms and more than 75 percent of bedrooms. Together with insects, a spider’s diet also consists of lizards, birds and even small mammals, depending on the species of spider. The high percentage of spider presence caused the two European biologists to ponder just how much food the entire world’s spider population consumes each year.

The estimate by Martin Nyffeler and Klaus Birkhofer was published in the journal The Science of Nature earlier this month, which caused the predictions to shock many readers. The biologists agreed that the world’s spiders consume somewhere between 400 million and 800 million tonnes of prey in any given year, which means that spiders eat at least as much meat as all of the 7 billion humans currently on earth combined. The authors also noted that humans consume around 400 million tonnes of meat and fish each year.
To conduct this insect investigation, Nyffler and Birkhofer came up with estimations after looking at existing research that states how many spiders live in a square meter of land for all the main habitat types on Earth, together with the average amount of food that is consumed by spiders of different sizes in a given year. Studies into the global average spider density came out at around 131 spiders per square meter, whilst studies into the weight of all the spiders on the planet points to a figure of around 25 million tonnes.

Despite these potentially quiver-inducing statistics for those with arachnophobia, spiders are actually a huge benefit to the planet. This is primarily due to the fact that they largely feast on an array of bugs, consuming approximately 10 percent of their body weight in food each day, according to spider biologists, which means that there are fewer pests in the garden, fewer mosquitoes in the yard and fewer flies in the house.