Cheiracanthium mildei

L. Koch, 1864

Northern Yellow Sac Spider, Long-legged Sac Spider

Cheiracanthium mildei is a -sized to Europe and North Africa, to North America and parts of South America. measure 7–10 mm in body length with pale green or tan coloration, darker and , and characteristically long legs up to twice the length of others. It constructs silken retreats rather than capture webs, hunting actively at night. The is frequently encountered in human dwellings, particularly in northern regions of its introduced range, and has been documented to bite humans with generally mild effects.

Cheiracanthium mildei, Nea Makri, Greece by Anna N Chapman. Used under a CC0 license.

Cheiracanthium mildei - spiderling 4 by Micha L. Rieser. Used under a Attribution license.

Cheiracanthium mildei male by Richard Bartz. Used under a CC BY-SA 2.5 license.

Pronunciation

How to pronounce Cheiracanthium mildei: /ˌkaɪrəˈkænθiəm ˈmɪldaɪ/

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Identification

Cheiracanthium mildei can be distinguished from the North C. inclusum by geographic origin and subtle morphological differences, though definitive identification often requires expert examination. It lacks the distinct groove and abdominal setal tuft present in Clubiona . identifying features include: pale green to tan body with darker mouthparts; legs significantly longer than others (up to 2× length); double on each leg; and with a distinctive canoe-shaped lucidum that reflects light. Males are recognized by modified resembling 'boxing gloves' and a leggier appearance.

Images

Habitat

Strongly associated with human dwellings in the northeastern United States and eastern Canada, where it is more often found inside than outside. In its European range, occurs in various including vegetation and artificial structures. Constructs silken retreats at wall-ceiling junctions and similar elevated indoor locations.

Distribution

to Europe and North Africa, extending through the Caucasus to Central Asia. to the United States (widespread across northeastern states and eastern Canada, also present in Washington state) and parts of South America. First introduction to the Americas likely occurred during periods of European .

Seasonality

Active year-round indoors in temperate regions; primarily with peak activity during nighttime hours. Spiderlings disperse after their next following from sacs.

Diet

of small and other ; hunts actively without constructing capture webs. Documented as a predator of in Africa and Middle Eastern regions, causing both direct mortality through consumption and indirect mortality through larval from plants.

Life Cycle

Females in a silken sac within a retreat. Spiderlings hatch and may return to the retreat after initial explorations, dispersing after their next . and males can be recognized by in leg proportions and male modification.

Behavior

Nocturnally active hunter that does not construct capture webs. Builds silken retreats ('sleeping bags') for daytime shelter, typically at wall-ceiling junctions; rarely reuses retreats, often constructing new ones after each night of activity. Capable of rapid movement across ceilings and vertical surfaces using tufts. Exhibits significant repellency to peppermint and variable responses to other (clove oil shows initial attraction at 24 hours becoming by 72 hours; lemongrass and citronella oils show attraction at 24 hours).

Ecological Role

controlling of small and . In agricultural contexts, contributes to of .

Human Relevance

Frequently encountered in homes, causing concern due to its appearance and rapid movements. Historically associated with necrotic bite rumors, but research has largely dismissed dangerous claims; bites are rare and effects appear mild, though large mouthparts can penetrate human skin. Secondary risk from any puncture wound remains a concern. Presence of retreats in corners creates aesthetic issues. Subject of research on natural including clove, ginger, and peppermint .

Similar Taxa

Cheiracanthium inclusum North with similar appearance and habits; C. mildei has replaced C. inclusum in northeastern U.S. houses and shows stronger tendency in northern climates while C. inclusum remains more common outdoors in southern states.
Clubiona speciesFormerly classified in same ; distinguished by presence of distinct groove and tuft of curved on margin, features absent in Cheiracanthium.
Cheiracanthium ilicisEuropean with similarly large mouthparts; C. ilicis shows exclusive association with Holm Oaks (Quercus ilex) while C. mildei is a synanthrope.

Misconceptions

Long considered at least mildly venomous to humans with potential for necrotic bites; research has demonstrated this is a myth. Bites are rare and effects are mild, though the 's large mouthparts can penetrate skin. The is often called an 'indoor spider,' but this is geographically variable—it is strongly in northern ranges but occurs commonly outdoors in its range and in southern climates.