Myrmekiaphila

Physical description and identification

Myrmekiaphila is a genus of mygalomorph trapdoor spiders in the family Euctenizidae, the wafer-lid trapdoor spiders. George Francis Atkinson erected it in 1886 on Alabama material, and about twelve species are recognised today: M. comstocki, M. coreyi, M. flavipes, M. fluviatilis, M. foliata, M. howelli, M. jenkinsi, M. millerae, M. minuta, M. neilyoungi, M. tigris and M. torreya. Together with Aptostichus in the west, it accounts for most of what the family looks like in the United States.

Two claims repeated online need correcting. The first is size: the widely quoted 0.28–0.8 cm is the carapace measurement from the taxonomic literature, not the length of the spider. The second is diet. The name comes from Greek myrmex, "ant", and philein, "to love", because Atkinson found the first burrows while collecting ants — not because these spiders specialise on them. They are generalist ambush predators.

Adults

• Size: a mature female is a solid animal of roughly 10–25 mm in body length, with a leg span reaching 40 mm or more. Males are smaller and lighter, with longer legs and swollen palpal tips.
• Colour: yellowish red through reddish brown to dark chocolate, the carapace darker and glossier than the abdomen. The legs are often a lighter tan, and M. flavipes takes its name from that pale-legged look.
• Markings: the abdomen commonly carries dusky transverse bands or soft chevrons on a paler ground, clearest on females — the grain of truth behind the widely quoted "females have dusky stripes".
• Eyes: eight small eyes bunched on a low mound at the front of the carapace, none enlarged. Eyesight is poor and hunting is done entirely by vibration — the opposite of a wolf spider, whose two large forward eyes reflect torchlight.
• Distinctive features: the fangs strike downward in parallel rather than pinching inward, the mygalomorph signature, and there are two pairs of book lungs. A rastellum, a rake of stout spines on the chelicerae, serves as the digging tool. Species identification needs an adult male and a microscope; the genus was last revised in 2007 by Jason Bond and Norman Platnick.

Eggs

The female mates in her own burrow and produces a silk egg sac that she keeps underground, sealed behind the door. She guards it in place rather than carrying it, and the shaft's stable humidity keeps the clutch from drying out.

Spiderlings

Spiderlings hatch below ground, pass their first moults in the mother's tube, then leave on foot to sink their own miniature burrows close by. They do not disperse on silk: ballooning belongs to the araneomorph spiders. Because dispersal happens at walking pace, populations are patchy and several species are confined to small parts of one or two states.

The burrow, not a web

No Myrmekiaphila spins a snare. The spider digs a silk-lined shaft, often angled rather than strictly vertical, and caps it with a thin, flexible wafer of silk and soil hinged along one edge — light and papery, unlike the thick bevelled cork plug used by the Halonoproctidae. The genus's real signature lies below: many species excavate a lateral side chamber part-way down, closed off by a second internal door, so a wasp that forces the front lid may still find an empty tube. At night the spider waits with the top door held a crack open and seizes anything that walks over it. For the contrast with true snare-builders, see our guide to spider webs.

Where Myrmekiaphila spiders live

The genus is endemic to the south-eastern United States, from northern Virginia and West Virginia down the Appalachians through Kentucky, Tennessee, the Carolinas and northern Georgia, and south across the coastal plain into Alabama, Mississippi and the Florida panhandle. Individual species occupy far smaller slices of that map: M. torreya and M. coreyi are Florida spiders, M. neilyoungi an Alabama one.

Habitat is more varied than the burrowing habit suggests — temperate deciduous forest, mixed pine woodland, mountain slopes, ravine sides, sandhills and stream banks all support the genus, provided the soil holds a shaft and drains after rain. Burrow entrances are almost invisible: field workers find them by feeling for the hinge line rather than by spotting a hole.

Are Myrmekiaphila spiders venomous?

Yes, in the sense that nearly every spider is: they have venom glands and use them to subdue prey. What matters medically is that no Myrmekiaphila venom is significant to people. There is no antivenom because none has ever been needed, and there are no verified reports of death, tissue damage or systemic illness.

Because Myrmekiaphila is a mygalomorph, it shares an infraorder with the genuinely dangerous Australian funnel-web spiders. That relationship is deep and distant and tells you nothing about risk: the medically serious mygalomorphs are Australian atracids, and nothing of the kind lives in a burrow in Alabama.

Can Myrmekiaphila spiders bite?

They can, but almost never do. A female spends her life sealed under a door, and her response to disturbance is to pull the lid down and hold it shut — a defensive posture, not an attacking one. Nearly every person who meets one of these spiders meets a wandering male on a garage floor or a porch step in autumn or winter.

A bite, on the rare occasions it happens, is mostly a mechanical event. Mygalomorph fangs are long, so the puncture can sting and bleed a little, followed by local pain, redness and mild swelling that settle within a day or two. No necrosis, no systemic envenoming, no antivenom. Wash the area with soap and water, apply a cold pack and take a simple painkiller if needed. Seek medical advice if redness spreads, pus develops or pain worsens after 24 hours, which indicates wound infection rather than venom.

Ecological importance and behavior of Myrmekiaphila spiders

Myrmekiaphila spiders are sit-and-wait ambush predators with an extreme attachment to one spot. A female may hold the same burrow for her whole adult life, deepening and re-lining it after each moult. Thousands of shafts on a forested slope aerate compacted soil and give rainwater a path downward.

Diet: ground-dwelling arthropods that walk within reach of the lid. Crickets, ground beetles, cockroaches, woodlice, millipedes, termites and ants all feature. It is worth repeating that ants are not a specialism — the "ant-loving" name describes where Atkinson was digging, not what the spiders prefer. Our overview of what spiders eat sets this in context.

Natural predators: the specialist enemy is the pompilid spider wasp, which works the door open, paralyses the spider and lays an egg on it; the side chamber and second door are widely read as a defence against exactly this. Centipedes also enter burrows, skunks and armadillos dig them out, and parasitoid flies take a further share.

Seasonal behaviour: unusually for a North American spider, the mating season falls in the cold half of the year. Males mature in autumn and wander through late autumn and winter, which is when almost all museum specimens of males were collected and why householders in the South meet them between November and February. Females remain below ground year-round and are long-lived; no such study exists for this genus, but trapdoor spiders elsewhere have been tracked for decades.

Relationship with humans: negligible and beneficial. These spiders will not colonise a house, they clear ground insects at no cost, and a wandering male found indoors is best released in shaded soil outside. The pressure runs the other way: with dispersal at walking pace, clearing one hillside can remove a meaningful share of a species' range.

Species in the genus and similar spiders

Quick facts

Did you know?

• George Francis Atkinson, who named the genus in 1886, is better remembered as a botanist and mycologist; the spiders were a by-product of his work on ants.
• Many species build a hidden side chamber sealed by a second door, giving the burrow an inner room the intruder never reaches — very few trapdoor spiders anywhere do this.
• The genus was revised in 2007 by Jason Bond and Norman Platnick, who named M. neilyoungi after Neil Young.
• Males wander in late autumn and winter, so the season for finding one in the South is the season when almost every other spider has gone quiet.
• Until 2012 the genus sat in Cyrtaucheniidae; a reassessment of mygalomorph classification that year moved the wafer-lid spiders into Euctenizidae.

In summary, Myrmekiaphila is the South's own wafer-lid trapdoor spider: about a dozen narrowly distributed species, built around a burrow with a hidden inner room, harmless to people, active in winter, and saddled with a name that describes a collector's habits rather than the spider's.