Spider Wasps

About 300 species in North America north of Mexico

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Glossy black spider wasp manipulating paralyzed spider
Spider wasps are nervous insects with long, spiny legs. They hunt spiders, which they paralyze with a sting. Then, they tuck it into a burrow, crevice, mud cell, or other hiding place and lay an egg on it. The wasp larva eats the spider before pupating into an adult.
David Cappaert, Bugwood.org
Other Common Name
Pompilid Wasps; Pompilids
Family

Pompilidae (spider wasps) in order Hymenoptera (ants, bees, wasps)

Description

Spider wasps are large wasps with long, spiny legs. Body color varies with species: most are dark — black, shiny blue-black, or brownish. Some species are black with yellow bands, or have orange or rust markings. The wings are often smoky-clear, amber, or dark like the body. Some species have orange or yellow legs or antennae.

To verify their identifications, specialists note details of wing venation, distinctive shapes and groove marks in the body plates, and features of the legs. For example, on the hind pair of legs, a spider wasp has two prominent spines at the outer end of the shinlike section (tibia) of the leg; these spines point outward toward the “foot” segments (tarsi). Also, the outer tip of the hind femur (analogous to the thigh), when stretched back, usually extends beyond the tip of the abdomen.

Similar species: There are many other kinds of dark-colored, medium to large wasps in our state. The extra long, spiny hind legs that often dangle downward in flight, and the nervous flicking of the wings are helpful characters for identification at a glance. The spider-hunting behavior, often on the ground, is another strong clue.

Size

Length: ¼ to 1½ inches.

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Female spider wasp grasping and dragging body of sac spider
Auplopus mellipes Spider Wasp With Prey
There about 10 North American spider wasp species in genus Auplopus. Members of this genus prey on sac, ground, crab, nursery web, or jumping spiders. They often snip off the legs of captured spiders, which makes them easier to move around. They typically craft mud cells for their young to develop in.

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Rusty spider wasp resting on a leaf
Rusty Spider Wasp
The rusty spider wasp, Tachypompilus ferrugineus, hunts wolf spiders (lycosids), usually in open areas. Females create nests in rock piles or in cracks in rock walls or foundation stones. Adults are often seen taking nectar from flowers.

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Blue-black spider wasp resting on senna foliage
Blue-Black Spider Wasp on Senna
This is one of nearly 50 North American species of blue-black spider wasps (genus Anoplius). Note the long legs, and the stout spines at the outer tip of the tibia segment of the hind legs.

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Black and rust-colored wasp on a plant
Poecilopompilus Spider Wasp
This spider wasp, Poecilopompilus algidus, like others in its genus, provisions its nests with orbweaver spiders. They dig nest burrows into the ground and therefore prefer sandy or other workable substrates.

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Black and rust-colored wasp resting on blackberry fruit
Blue-Black Spider Wasp on Blackberry Fruit
This blue-black spider wasp might be Anoplius americanus, which has different regional color forms across North America. Females hunt wolf spiders on the ground, flicking their wings nervously. These wasps are often seen visiting flowers.

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Long-legged wasp grasping a wolf spider while clinging to house siding
Entypus Spider Wasp
The spider wasp Entypus unifasciatus, like others in its genus, has a blue-black body, smoky wings with orangish tips, and bright yellowish orange antennae. Note the long, spiny legs! They typically hunt wolf spiders to provide food for their larvae.

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Rusty spider wasp dragging a wolf spider across the ground
Rusty Spider Wasp With Prey
The rusty spider wasp (Tachypompilus ferrugineus) hunts members of the wolf spider family. The favorite prey are Rabidosa rabida and Tigrosa helluo; this looks like the latter. The female rusty spider wasp drags the paralyzed spider backwards, grasping it by its fangs or pedipalps (fingerlike appendages next to the mouth).

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Black spider wasp dragging an orbweaver spider on a plant stalk
Episyron Spider Wasp With Prey
Spider wasps in genus Episyron prefer to hunt orbweaver spiders — the kind that spin circular webs. This is species Episyron quinquenotatus, and her prey might be a furrow orbweaver (Larinioides sp.).
Habitat and conservation

Spider wasps occur in a variety of habitats. Species that dig in the ground are usually found in places with loose, workable soil.

With their jerky movements, large size, long legs, and often shiny-black bodies, spider wasps attract the attention of people. Most people see spider wasps as they visit flowers for nectar, or when they walk around on the ground, nervously flicking their wings, hunting for spider prey. Often people spy a female spider wasp as she’s dragging a paralyzed spider to her burrow or other storage place, where the spider’s body will provide food for a larval wasp.

Foods

As a larva, a spider wasp eats the body of the spider its mother captured for it, which is enough food for the larva to grow to its full size and begin pupation. Because each larva is provisioned with only one spider, the spiders are generally about the same size as the adult wasp. Most spider wasps prey on free-living spiders (not the kinds that live in webs) — for example, tarantulas, wolf spiders, crab spiders, and jumping spiders — but others capture orbweavers, grass spiders (funnel web weavers), or others. In general, different types of spider wasps specialize in different types of spiders.

As adults, spider wasps sustain themselves by drinking sweet nectar from flowers but may also take juices from fallen or overripe fruit or take sweet honeydew secreted by aphids.

Distribution in Missouri

Statewide. Different species have different distributions.

Status

Taxonomically, the spider wasp family is grouped in the same superfamily as the velvet ants (family Mutillidae), myrmosid wasps (family Myrmosidae), and sapygid or “club-horned” wasps (Sapygidae). Thus they are less closely related to other wasps such as paper wasps, potter wasps, mud daubers, yellowjackets, and hornets.

Scientists suspect that spider wasps represent some of the earth’s more ancestral wasps. (Scientists used to use the term “primitive.”) Compared to the amazing social organization, prey-carrying, and nest-building capabilities of paper wasps, yellow jackets, and other vespid wasps, spider wasps — dragging their prey backward over the ground, digging a special hole for each egg — have rather rudimentary skills.

Life cycle

Pompilids are solitary wasps and do not nest in colonies. Males typically hold territories and perch, waiting for receptive females to fly near and fending off rival males. After mating, the female spider wasp locates a suitable prey spider (each species typically has a certain group of spiders it usually hunts) and subdues it by stinging it. She then drags the paralyzed spider to a nest chamber.

Different species use different types of nest chambers. Some females dig burrows into the ground, others build mud cells or use abandoned cells of mud daubers, others use preexisting holes (such as beetle-bored holes in tree trunks, or old burrows of moles or mice), and some use the spider’s own nest or cranny. Some species snip off some or all of the spider’s legs to make it easier to drag around. With the spider tucked away, she lays an egg on it, closes the nest entrance, and repeats the process for each egg she lays.

Upon hatching, the grublike larva chews on the spider’s body, which provides the nourishment for it to grow to full size. Interestingly, the larva generally avoids eating the spider’s vital organs until it’s almost fully grown, which keeps the spider alive and fresh. The larva pupates inside a silken cocoon, and in most species, this is the form that overwinters.

Human connections

Wowie, zowie! These large, long-legged spiders attract attention as they drag their captured prey — often a good-sized spider — to its doom. We usually think of spiders as fierce (though smallish) predators, but this is a reminder that in nature, the predator is also often also the prey.

Although spider wasps are rated as having one of the most painful insect stings, they are not aggressive to people. Unlike social wasps, where many females work together to build communal nests and defend the nest vigorously, spider wasps are laser-focused on their mission to find, capture, and hide their spider prey. Female spider wasps usually only sting people who are attempting to handle them or are otherwise distressing them bodily.

Males (which cannot sting) may look imposing when they buzz around, chasing away intruders, but although they may fly toward us for an inspection, they do not attack people.

The parasitoid life cycle, where a mother lays an egg on a host, and the larva devours the living host, has been the inspiration for many grotesque science fiction monsters, such as the creature in the Alien movies.

In the early 1900s, entomologists — including Missourian Phil Rau — noted an unusual sight: a wasp flying very low over a stream, dragging a spider across the surface film like a wind skier. It remained a "mystery species" among insect geeks until entomologist and nature writer Howard Ensign Evans identified it as Anoplius depressipes, one of the “blue-black spider wasps.” It turns out this species hunts fishing spiders (Dolomedes spp.) and possesses specialized flattened front feet that are fringed with hairs, which allow it to walk on water, just like its prey. When transporting a spider, this species grasps the spider with its middle or hind legs, faces forward, then extends its forelegs and uses them like water skis while it propels itself and its prey across the top of the water, beating its wings. (Ahoy, matey!) This spider wasp sometimes dives down into water to chase its prey, since water spiders often swim underwater when frightened. Not surprisingly, it nests in burrows in stream banks.

Ecosystem connections

Spider wasps are conspicuous and usually have warning colorations (usually combination of black and yellow, orange, or red) that help “educated” would-be predators of their ability to sting. Apparently, in some species, even the males (which do not possess stingers) have a disagreeable smell or taste. Once a flycatcher (for example) is stung by a black-and-orange spider wasp, it knows to avoid similar-looking insects. Many other insects that are perfectly edible and harmless gain protection from predators by having the same coloration, body shape, and even flying style of spider wasps. Mydas flies are an example of these mimics.

Spider wasps are called parasitoids because their larvae, like parasites, take nourishment from a living host — but unlike typical parasites, they ultimately kill their hosts (hence the word’s “-oid” ending). Other parasitoid animals include tachinid flies, some types of ground beetles, and ichneumon and braconid wasps. (Braconids are the insects that are famous for eating a hornworm’s body juices from the inside, then pupating in small silken cocoons on the caterpillar’s outer skin.)

In some cases, if a spider stung by a spider wasp manages to escape being buried with an egg on it, the spider can eventually recover and survive its brush with doom. Numerous studies have been made of the stinging behavior of various spider wasps; some use a few quick stings to initially subdue a spider, then administer another sting, slowly, into the underside of the front of the body, where the nervous system is most concentrated. After that, the spider is probably a goner.

Tarantula hawk wasps (Pepsis and Hemipepsis spp.) are in this family, and they are famous for their large size, long stingers, and excruciating stings (should anyone dream of handling them). They specialize in capturing tarantulas, so these wasps are most numerous and diverse in the desert southwest, where tarantulas are abundant. If you go to the desert southwest, keep an eye out for these huge insects! (Or, look for videos of their battles online.)

One species of tarantula hawk is found throughout the eastern United States: the elegant tarantula hawk (P. menechma). It feeds, however, mostly on trapdoor spiders, not tarantulas. It is glossy blue-black with bright yellow antennae. Also, the southwestern species P. pallidolimbata has been found in southwestern Kansas and central Nebraska, so it’s not unreasonable to think that it might eventually be seen in southwest Missouri — the part of our state where tarantulas are most abundant.