Invertebrates
Jerusalem Cricket
Ammopelmatus · also called potato bug, child of the earth, nino de la tierra
Few insects unsettle people the way the Jerusalem cricket does. It is big, it is flightless, it has a bald, shiny, weirdly human-looking head, and it turns up unexpectedly when you dig in the garden. It is also entirely harmless, misnamed twice over, and a drummer.
Overview
The Jerusalem crickets are a group of large, wingless, burrowing insects of western North America and Mexico, living in loose soil from deserts to gardens. A typical one is 3–5 cm long, with an amber, oddly humanoid head, big jaws, a black-and-amber banded body, and thick spiny digging legs. It eats roots, decaying matter, and other insects underground.
Neither a cricket nor from Jerusalem
It is not a true cricket — it has its own family — and it has no connection to the Middle East; the name may be a mangled Navajo phrase or an old exclamation.
The drummer
Having no wings to rub together, it communicates by drumming its abdomen on the ground in species-specific rhythms; a male and female tap back and forth to find each other in the dark. It cannot sting, but its jaws can deliver a hard, painful nip, so it is best not handled.
Status
Least Concern — the dozens of species are common, though most have never been formally assessed.
Jerusalem Cricket: common questions
Are Jerusalem crickets dangerous or venomous?
No. A Jerusalem cricket has no venom, no sting, and no way to seriously hurt a person. What it does have is a set of strong, blunt jaws built for chewing roots and prey underground, and if you pick one up and it feels threatened it can clamp down hard enough to break the skin and leave a bruise, so the sensible thing is not to handle it barehanded. It may also give off an unpleasant odour as a deterrent. Beyond a painful pinch, it is completely harmless, and it plays a useful role turning over soil and recycling dead plant and animal matter.
Why is it called a Jerusalem cricket if it is not a cricket and not from Jerusalem?
The name is a puzzle with no agreed answer. The insect is native only to the Americas and has no connection to the Middle East, and it is not a true cricket but a member of a separate family sometimes grouped with the wetas and king crickets. One idea is that "Jerusalem" was a mild exclamation, like "Jerusalem crickets!" as a substitute for a curse, that got attached to the startling-looking bug. Another traces it to a mistranslation of a Navajo name. The many other names, potato bug, child of the earth, old bald-headed man, skull insect, reflect how strange and unsettling people have found it.
What is the drumming for?
It is how Jerusalem crickets find and choose a mate in the dark, underground world they live in. True crickets and katydids sing by rubbing body parts together, but Jerusalem crickets are wingless and cannot do that, so instead they beat the underside of the abdomen against the soil, producing a low thumping that travels as vibration through the ground. Each species has its own tempo and pattern, and a male and a receptive female drum alternately, homing in on each other by the exchange. After mating, the female sometimes eats the male, and she lays her eggs in a chamber in the soil.
I found one in my garden. Should I move it or kill it?
Leave it, or gently relocate it with a trowel if it is somewhere inconvenient. Despite the "potato bug" name, Jerusalem crickets rarely do meaningful damage to garden crops; they nibble roots and tubers opportunistically but are mostly eating decaying material and soil insects, and their tunnelling aerates the ground. They are also food for owls, skunks, coyotes, and other wildlife. A Jerusalem cricket turned up by a spade is simply a native insect going about its business, and the alarming face and the folklore around it are not reasons to harm it.