Myths, squashed
Eight things people often say about creepy-crawlies, and what the sources actually say. Checked on 24 Oct 2026.
Spiders are insects.
Spiders are arachnids, not insects. Count the legs: insects have six, spiders have eight.
Every adult insect has a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae. [source] Spiders have eight legs, fangs that can usually inject venom, and spinnerets that make silk. [source] Spiders belong to the arachnids, along with scorpions, ticks, mites and harvestmen. [source]
Centipedes have 100 legs.
None of them do. The number of pairs is always odd.
No centipede has exactly 100 legs. They always have an odd number of pairs, from 15 to 191. [source]
Millipedes have 1,000 legs.
For a long time, none were known to. Then one turned up with even more.
“Millipede” means “thousand feet”, but no millipede was known to have 1,000 legs until Eumillipes persephone was discovered in 2020, with over 1,300. [source]
Glow-worms are worms.
They’re beetles.
Glow-worms aren’t worms at all. They’re beetles, and the wingless females glow to attract males. [source]
Woodlice are insects.
Every creepy-crawly is a bug.
In everyday speech, sure. To an entomologist, a “true bug” is one particular order of insects.
To a scientist, “true bugs” are just one order of insects, the Hemiptera, which includes aphids, cicadas and shield bugs. They all have piercing, sucking mouthparts. [source]
A stag beetle will give you a nasty bite.
The big-jawed males can’t really hurt you. It’s the females you should handle with care.
A male stag beetle’s huge jaws look like a stag’s antlers and are used in fights with other males, but they’re too weak to hurt you. Females can give a painful nip. [source]
A slug is just a snail that lost its shell.