What Does a Brown Recluse Look Like? Violin Mark and Six Eyes

The violin mark

The brown recluse (Loxosceles reclusa) is nicknamed the fiddleback or violin spider because of a dark brown mark on its cephalothorax, the front part of the body to which the legs attach. The broad base of the “violin” sits just behind the eyes, and its neck points backward toward the abdomen.

The mark is usually clear in adults and darkens with age, but it can be faint in young spiders and pale individuals. It is also the least reliable clue. Many harmless spiders have dark shapes on the cephalothorax that people read as a violin, so experts recommend checking the eyes, legs and abdomen as well.

Six eyes in three pairs

The eyes are the best single feature. Most spiders have eight eyes, but recluse spiders have six, grouped in three pairs called dyads: one pair at the front and one pair on each side, separated by gaps and arranged in a shallow U shape. Because the eyes are tiny, you usually need a magnifying glass or a sharp close-up photograph to see them.

A few other spiders also have six eyes, notably spitting spiders and the woodlouse spider, but they look different in other ways, as described below.

Body, legs and color

Recluses are surprisingly plain spiders. The key features are:

• Color: light to medium brown overall, from cream to dark brown in some individuals. The cephalothorax and abdomen do not always match exactly.
• Abdomen: oval, evenly colored, with no stripes, spots or chevrons. It is covered in fine, short hairs that give it a smooth, slightly velvety look.
• Legs: long and slender, the same color from base to tip, with fine hairs but no thick spines and no bands.
• Posture: at rest, a recluse usually stands with all legs spread out around the body.

Males and females look alike. Males have slightly smaller bodies, relatively longer legs and, when adult, enlarged dark palps, the feelers beside the jaws, which look like small boxing gloves.

Size: when a spider is too big to be a recluse

Most adult brown recluses have a body about 6–13 mm (0.25–0.5 in) long, typically around 9 mm (3/8 in). With legs spread, a large one is roughly the size of a coin. Some references quote larger figures, but recluse specialists say that a spider with a body clearly longer than about 13 mm (1/2 in) is very unlikely to be a brown recluse. Big, heavy, hairy brown spiders are almost always wolf spiders, fishing spiders or house spiders.

Common look-alikes

Many harmless spiders are mistaken for brown recluses. The most frequent ones are:

• Wolf spiders: larger, stocky and hairy, with stripes or mottled patterns and eight eyes, including two very large ones facing forward. They run across floors and lawns at night. The biggest North American species is the Carolina wolf spider.
• Cellar spiders: tiny bodies on extremely long, thin legs; they hang upside down in loose webs in corners. Some have a dark mark on the cephalothorax that looks a little like a violin.
• Grass spiders and other funnel weavers: two dark stripes along the cephalothorax, a patterned abdomen and spiny legs. They build flat sheet webs with a funnel, often out in the open on lawns and shrubs.
• Southern house spider (males): tan, long-legged spiders of the southern US that wander indoors; they have eight eyes in a tight cluster and no violin.
• Woodlouse spider: has six eyes, but its cephalothorax and legs are a striking reddish orange and its abdomen is pale cream or gray, with large jaws for piercing woodlice.
• Spitting spiders: also six-eyed, but with a domed, spotted cephalothorax and banded legs.

In Europe and the Pacific Northwest, large brown spiders indoors are usually house spiders such as the giant house spider, which is much hairier and has banded, spiny legs.

Webs, behavior and other clues

Brown recluses do not build orb webs or sheet webs in the open. They spin small, irregular retreats of loose, off-white silk in hidden places, such as behind boxes, in closets and in the corners of attics and sheds. A spider sitting in a conspicuous web between plants or across a doorway is not a recluse.

Recluses are active at night and hide by day. Another clue is their shed skins: pale, papery, ghost-like copies of the spider that collect where recluses live. Location matters too. Outside the south-central and lower Midwestern US a brown recluse is very unlikely, so check where do brown recluse spiders live?

What to do if you think you have found one

Do not pick up or handle a spider you suspect is a recluse. A clear photograph showing the eyes and legs, or a spider safely collected in a sealed container, can be identified by an entomologist, for example at a university extension office or a natural history museum. Remember that recluses are shy and bite only when trapped against skin; for the real risks, see how dangerous is a brown recluse?