Invertebrates
Tarantula Hawk
Pepsis grossa · also called tarantula hawk wasp, pepsis wasp
The tarantula hawk is a large, elegant wasp with a dark metallic body and bright orange wings, and it has two claims to fame: it hunts tarantulas far bigger than itself, and it delivers what may be the most painful sting of any insect on Earth.
Overview
Tarantula hawks are spider wasps found across the warmer regions of the Americas and, in related species, Africa, Asia, and Australia — anywhere tarantulas live. Adults are common in deserts, grasslands, and scrub, where they are often seen unhurriedly feeding on flowers, especially milkweeds and mesquite. They are solitary; there is no colony, no nest of workers, just individual females each provisioning burrows for their own offspring.
Hunting a giant
A female tarantula hawk’s job is to find one tarantula per egg. She searches the ground and follows the spider’s silk trails to its burrow, then provokes the tarantula until it rears into a defensive posture. In that instant she strikes, stinging into the thin membrane at a leg joint and injecting a venom that induces immediate and lasting paralysis while leaving the spider alive.
She then hauls the limp spider — which may outweigh her several times over — to a burrow, lays a single egg on its abdomen, and seals the chamber. The grub that hatches consumes the living, paralysed tarantula over several weeks, feeding on the least vital tissues first so its food does not die and spoil.
The sting
On the Schmidt sting pain index, which runs from 1 to 4, the tarantula hawk scores a 4.0 — matched only by the bullet ant and the warrior wasp. Justin Schmidt, who was stung in the course of his research, described it as instant, total, electrifying pain, and recommended lying down to avoid falling over. Crucially, the sting causes almost no lasting harm and the pain subsides within about five minutes; it is agony without injury, a pure deterrent.
The wasp’s conspicuous colouring advertises that deterrent, and it works: tarantula hawks have almost no predators. Roadrunners and a few other birds are among the rare animals willing to eat one.
Adult life
Adult tarantula hawks feed only on sugar — nectar and, notably, fermenting fallen fruit, on which they can become visibly intoxicated and clumsy. Males patrol hilltops and tall plants, waiting for females, and cannot sting; only the female carries the modified egg-laying sting.
Status
The tarantula hawk is Least Concern and common. It plays a role as a pollinator of desert plants and as a natural check on tarantula numbers, and it is celebrated enough to be the state insect of New Mexico. It faces no significant threats beyond the general effects of habitat loss and pesticide use on insect populations.
Tarantula Hawk: common questions
How painful is a tarantula hawk sting?
It is one of only a handful of stings rated 4.0 — the top of the scale — on entomologist Justin Schmidt's sting pain index. Schmidt described it as "blinding, fierce, shockingly electric" and advised anyone stung to simply "lie down and scream." The good news is that the agony, while overwhelming, lasts only about five minutes and then fades, and the venom does very little tissue damage. Unless you are allergic, a tarantula hawk sting is far more traumatic than it is dangerous.
How does a wasp overpower a tarantula?
The female tarantula hawk actively seeks out a tarantula, often by following the spider's silk draglines to its burrow, and taps and provokes it into a defensive stance. When the spider rears up, she darts in and stings it in the soft membrane near a leg joint, injecting a venom that causes near-instant, permanent paralysis without killing it. She then drags the immobilised spider — which can weigh far more than she does — back to a burrow she has prepared or to the spider's own den.
Why keep the tarantula alive?
Fresh meat. The wasp lays a single egg on the paralysed but living spider and seals it in the burrow. When the grub hatches it feeds on the spider from the outside and then bores in, and it eats the non-essential tissues first — fat, muscle, digestive organs — leaving the heart and nervous system until last so the spider stays alive and un-rotted for as long as possible. The spider is consumed over several weeks, after which the grub pupates and emerges as an adult wasp.
Are tarantula hawks aggressive toward people?
No. Despite the fearsome sting, tarantula hawks are docile and slow to sting, and they only do so in self-defence when grabbed or trodden on. Males cannot sting at all (only females have a sting, which is a modified egg-laying organ). Adults spend most of their time feeding calmly on flowers, and the state of New Mexico chose the tarantula hawk as its official state insect.