Sac-like spiders, Cheiracanthiidae (represented by genera such as Cheiracanthium).

Detailed introduction

Sac spiders are a large group of spiders that like to rest by weaving "sacs" in leaves or crevices. They mainly include the family Cheiracanthiidae and some closely related groups (such as bag spiders in the family Clubiona ). The "yellow sac spider" or "small yellow spider" that people often refer to usually refers to some pale yellow species in the Cheiracanthiidae family.

Basic Information

• Representative scientific name (general term): Family Cheiracanthiidae – Cheiracanthidae (typical genera such as Cheiracanthium , etc.)

• Common Chinese names: Yellow-sac spider (for yellow species)

• Common English name: Sac Spiders / Yellow Sac Spiders

• Size: Body length is usually about 4–10 mm, a few species may be slightly larger, and leg span is about 1–2 cm.

• Lifespan: Most small species can live for 1–2 years, and female spiders can produce multiple egg sacs in their lifetime.

Silk Sacs and Living Habits

The name "sac spider " comes from the silk sacs they habitually weave. Unlike garden spiders, which rely on large webs to catch prey, sac spiders are mostly hunting spiders that do not weave large webs . Instead, they weave a small, flat silk sac on the back of leaves, in grass, in crevices in walls, or on the surface of objects.

• During the day, the silkworm spider will hide in its silk sac to rest or molt;

• Female spiders typically lay their eggs in a silk sac and guard the sac.

• At night, they emerge from their silk sacs and actively roam on plants or walls to prey on insects.

Appearance features

Most yellow-sac spiders are small in size, with a slightly elongated oval body and relatively long legs, though not as extremely long as those of long-legged spiders. Common body colors of the "yellow-sac spider" are:

• Pale yellow, milky white, or light yellowish-green body color;

• The cephalothorax is slightly dark, sometimes tinged with light brown or olive green;

• The abdomen is relatively smooth, and some species may have inconspicuous spots or lines.

The silkworm spider is agile and can quickly escape along leaves or walls when startled, or hide back in its silk sac.

Distribution and Habitat

Scaly spiders are found almost globally , but are particularly common in temperate and tropical regions. They can be found in a variety of habitats:

• On the leaves and branches of forests and shrubs;

• Crop leaves in farmland, grassland and orchard;

• Near gardens, green belts, walls, fences, and outdoor lighting fixtures;

• Some species will even venture indoors, weaving small silk sacs in corners, window frames, or furniture crevices.

Diet and ecological role

The sac spider is a typical nocturnal hunting predator , primarily preying on:

• Plant pests such as aphids, leafhoppers, and small beetles;

• Various small flying insects and small arthropods of the class Arachnida;

• They also occasionally prey on slightly larger insect larvae or other small spiders.

Therefore, many burrowing spiders are considered a natural biological control force in farmland and horticultural systems, helping to suppress pest populations and serving as important small natural enemies in the ecosystem.

Toxicity and its effects on humans

Yellow-sac spiders possess venom glands used to paralyze their prey. Some species of yellow-sac spiders have been reported in medical literature for occasional bites, and their venom has been suspected of causing local necrosis or more severe skin reactions.

Current clinical studies show that most cyst spider bites only cause localized pain, redness, and a mild burning sensation . A small number of people may experience more extensive erythema or discomfort lasting for several days, but severe systemic poisoning is very rare. Overall, they are not considered highly dangerous spiders.

Contact with humans and protection

People often see the small silk sacs spun by sac spiders during the day in gardens, near fruit trees, crops, and outdoor lighting fixtures. Unless deliberately squeezed or grasped, the sac spiders will usually flee quickly rather than attack.

In areas where burrowing spiders are known to be abundant, the following simple protective measures can be taken:

• Before tidying up flower pots, removing leaves, or turning over gardening tools, gently shake or inspect them.

• Try to avoid pinching the small "white sacs" on the back of the leaves with your bare hands;

• If you suspect you have been bitten by a spider, wash the wound with clean water, observe the symptoms, and seek medical attention if necessary.