Hogna

Physical description and identification

Hogna is the largest and most widely distributed genus of wolf spiders (family Lycosidae). Eugène Simon erected it in 1885, and more than 200 species are now recognised, on every continent except Antarctica. The best known are the Carolina wolf spider (Hogna carolinensis), the biggest wolf spider in North America, and Hogna radiata of the Mediterranean.

Adults

• Size: body length runs from about 10 mm in the smaller species to roughly 35 mm in the largest females, with males always smaller and slimmer. Figures of 12 cm that circulate online refer to leg span, not body length: a very large female spans about 100–120 mm from foot to foot, which is why Hogna is so often mistaken for a small tarantula.
• Color: most species are brown, grey-brown or sandy, patterned to match local soil. A pale or dark median band on the carapace is usual, and many species have banded legs. The underside is diagnostic in some: H. carolinensis has a solid jet-black belly, while several relatives are pale or striped beneath.
• Eyes: eight eyes in the lycosid three-row pattern — four small eyes in a low front row, two very large forward eyes above them, and two medium eyes on top of the head. The large eyes carry a reflective tapetum, so a torch held at eye level turns a field of Hogna into a scatter of green sparks. See spider eyes for how that works.
• Distinctive features: a heavy, thick-set build with stout bristly legs, long dark chelicerae and a dense coat of fine hairs. Most species can be named only on adult genitalia; colour and size overlap far too much to identify one from a photograph.

Eggs and egg sacs

The female builds a rounded, pale egg sac and attaches it firmly to her spinnerets, then drags it behind her for two to four weeks. A large H. carolinensis sac can contain several hundred eggs. She tilts it towards the sun and will not abandon it; burrowing females block the entrance and sit with the sac in the shaft.

Spiderlings

The mother opens the sac when the young are ready. They climb onto her abdomen and cling there in layers for one to three weeks on their yolk reserves, then leave gradually to hunt alone. Many disperse on foot, and small species also balloon on strands of silk. They grow by repeated moulting and generally mature the following year.

Burrows instead of webs

No Hogna spins a capture web. The genus splits roughly into two lifestyles. Burrowers such as H. carolinensis dig a vertical shaft 20–60 cm deep, line it with silk, and sometimes build a turret of pebbles and plant fragments around the rim; the spider waits at the entrance after dark and grabs whatever passes. The rest are free-roaming hunters that shelter under stones, logs and litter. In both cases silk is used only for the burrow lining, the dragline and the egg sac — never to trap prey, which is what separates them from the sheet-web funnel weavers they are often confused with.

Where Hogna spiders live

Hogna is close to cosmopolitan. Species occur across North and South America, throughout Africa, around the Mediterranean and into temperate Europe, across Asia from Kazakhstan to Japan, and in Australia and the Pacific. Island endemics are a feature of the genus: H. hawaiiensis in Hawaii, H. galapagoensis in the Galápagos, H. canariana in the Canaries and H. maderiana on Madeira, with more on St Helena and the Balearics.

Habitat preference is broad but always terrestrial and open. Grassland, prairie, desert scrub, dunes, scree, field margins, gardens and forest floor all support species, and burrowing forms need soil loose enough to dig but firm enough to hold a shaft. In the United States they are common across the south and west, from Arizona and Texas to the Carolinas, and H. radiata is one of the most frequently reported large spiders of Greece, Italy and Spain.

Are Hogna spiders venomous?

Yes, and like nearly all spiders they use venom to subdue prey — in the large species that can mean beetles, crickets, grasshoppers, other spiders and occasionally a small lizard or frog. The venom is not medically significant to humans. No antivenom exists for any wolf spider because none is required, and reviews of verified bites place Lycosidae among the groups that produce local pain without systemic illness. Older European literature blamed Hogna and its relatives for necrotic wounds; that claim has not held up, and modern clinical work attributes such lesions to other causes.

Can Hogna spiders bite?

They can, and because the fangs of a large female are genuinely big, the bite is felt. It still takes provocation. A cornered Hogna will first run, then rear up on its back legs with the front pair raised and the fangs spread — a bluff that ends the encounter far more often than a bite does. Most real bites happen when the spider is picked up, stepped on barefoot, or pressed against skin inside a boot or glove.

Expect sharp pain like a deep pinprick, redness, mild swelling and sometimes itching, all settling over a day or two. Wash with soap and water, apply a cold pack and use a simple painkiller if needed. Seek medical care if the pain is severe or spreading, if swelling grows after the first day, or if there is breathing difficulty or a widespread rash, which point to an allergic reaction rather than the venom. A photograph of the spider rules out the species that do matter.

Ecological importance and behavior of Hogna spiders

Hogna species are among the heaviest invertebrate predators of open ground. They hunt at night by sight and by vibration, taking crickets, grasshoppers, beetles, moths, cockroaches, ants and other spiders, and the largest species occasionally take small vertebrates. Because a single burrow can be occupied for a year or more, a population is stable and its effect on local insect numbers is steady rather than seasonal.

Natural predators: spider wasps of the family Pompilidae are the great specialist enemy, dragging a paralysed adult into a nest as food for a single larva. Birds, lizards, snakes, toads, shrews and skunks take them, and parasitoid flies and wasps attack the egg sacs. See what eats spiders.

Prey-predator dynamics: burrow-dwellers are ambushers with a fixed address, while the roaming species are searchers. The two strategies split the same ground between them, and both are strongly cannibalistic — a large Hogna readily eats a smaller wolf spider, which is why juveniles disperse early.

Seasonal behaviour: in temperate regions adults mature in late summer and autumn. Males abandon their shelters to search for females, drumming their palps outside a burrow entrance in a species-specific rhythm, and rarely survive the winter. Females of the larger species can live two or three years, plugging the burrow and going dormant through cold weather.

Relationship with humans: harmless and useful. A wandering male indoors is best cupped and released. Conservation matters for at least one member of the genus: Hogna ingens, the Deserta Grande wolf spider of Madeira, is confined to a single valley and is listed as Critically Endangered.

Species in the genus and similar spiders

Quick facts

Did you know?

• Eugène Simon, who named the genus in 1885, described more spider species than anyone before or since.
• Tigrosa helluo spent most of its history as Hogna helluo; the genus Tigrosa was split off in 2012 for a group of large eastern North American species.
• The Carolina wolf spider is the official state spider of South Carolina, the only US state to have designated one.
• Hogna ingens, the Deserta Grande wolf spider, survives only in one valley of a small Madeiran island and is one of the few spiders anywhere listed as Critically Endangered.
• The eyeshine of a Hogna carries tens of metres, and counting sparks by torchlight is the standard field method for surveying them.

In summary, Hogna contains the giant wolf spiders: over 200 species of powerful, night-hunting ground spiders that dig burrows, carry their spiderlings on their backs and eat an enormous quantity of insects. They look formidable and one or two rear up impressively, but the bite is a painful pinprick, not a medical emergency.