Identification: the orange spider with unusual jaws
Dysdera crocata is one of the easiest BC spiders to identify in the field. The colour combination is distinctive: a deep orange-red to rust-coloured cephalothorax (head-thorax) and legs, paired with a pale cream to off-white abdomen. The contrast is striking and unlike any other common BC spider. But the most remarkable feature is the chelicerae — the jaw structures that hold the fangs. In most spiders, the chelicerae are proportionate to the body. In Dysdera, they're enlarged to an exaggerated degree, pointing forward and downward in a posture that looks threatening even to seasoned observers. The chelicerae are the spider's adaptation for piercing the hard armour of woodlice prey.
Body length is 10–15 mm for females, slightly smaller for males. The spider is oval-bodied, hairy, and relatively robust. It has six eyes (not the typical eight of most BC spiders) arranged in a distinctive oval cluster. Six-eyed spiders are uncommon in BC — this is a useful confirming feature alongside the colour pattern.
| Species | Colour | Size | Distinguishing feature |
|---|---|---|---|
| Woodlouse hunter (Dysdera crocata) | Orange-red cephalothorax, pale abdomen | 10-15 mm | Huge chelicerae, 6 eyes, pill bug habitat |
| Red-backed jumping spider (Phidippus johnsoni) | Black with red abdomen | 8-12 mm | Red abdomen (not cephalothorax), large front eyes |
| Araneus diadematus (cross orb-weaver) | Variable brown-orange | 10-15 mm | Spiral orb web, cross marking on abdomen |
| Some wolf spiders (Lycosidae) | Reddish-brown tones possible | 12-25 mm | Ground hunter, carries eggs, eye-shine |
Ecology: a specialist predator
Dysdera crocata is a specialist: it evolved specifically to hunt woodlice (isopods — pill bugs, sow bugs, slaters). Woodlice have a tough, segmented armour that resists most spider bites. Dysdera's oversized chelicerae allow it to bite around or through the armour from the side or underside. The spider is nocturnal and typically hunts in the leaf litter and under rocks and boards where woodlice concentrate. It builds a small silk retreat — a retreating tent of silk under a rock or board — where it rests during the day and where females lay eggs.
In Metro Vancouver, Dysdera is common in gardens with established woodlouse populations — compost areas, stacked wood, old stone walls, garden borders with organic mulch. It was introduced from Europe (where it's similarly ubiquitous) and is well-established across the Lower Mainland, Vancouver Island, and southern BC. It's a beneficial garden predator: woodlice in gardens become pests when they chew seedlings, and Dysdera helps regulate their population.
Does it come indoors?
Dysdera occasionally enters buildings but is not primarily an indoor species. When found indoors it's typically in basements, crawlspaces, or utility rooms — the same damp environments where woodlice concentrate. A Dysdera indoors is typically following its prey. It doesn't build large webs indoors (it builds only a small silk retreat) and doesn't establish the persistent indoor populations that house spiders do. Finding one or two Dysdera in a basement is incidental; finding multiple across multiple seasons suggests a woodlice population that's drawing them in.
Bite risk: the big chelicerae question
Dysdera's large chelicerae raise the natural question: can it bite, and does it? Yes on both counts — more readily than house spiders, and the bite is more significant than a typical BC spider bite. Dysdera has sufficient chelicerae development to easily penetrate human skin, and bite reports in the scientific literature describe pain that can persist for several hours, sometimes with significant local swelling. There's no venom component that produces necrosis or systemic effects in healthy adults.
In practice, Dysdera bites humans when it's handled or when it's accidentally compressed against skin — reaching under rocks or boards without checking is the typical scenario. Woodlouse hunters are not aggressive toward humans and would far rather flee than bite. But if surprised or squeezed, they can produce a more memorable bite than you'd expect from a 12 mm spider. The recommendation: check under garden rocks, boards, and landscaping features before bare-hand reaching, particularly in summer when Dysdera is most active.