Cheiracanthium inclusum

Geographic Range

Yellow sac spiders (sometimes known as agrarian sac spiders) are found throughout North and South America, including Mexico and the West Indies, United States, and southern Canada. There are also accounts of yellow sac spiders being found in Africa, which indicates that it may be an introduced species to that continent. (Barnes, 2003; Hogg, et al., 2010; Jacobs, Sr., 2006; Jones, 2004)


Yellow sac spiders form silk tube-like sacs under ground debris and within man-made structures, hiding within these tubes during the day. Alternatively, the spiders may roll themselves up in leaves or other debris during daytime hours or in other tight places providing protection. This species occupies a wide variety of habitats, including trees, forest floors, fruit orchards and other agricultural areas, and shrubs surrounding open fields (most of the biomes within the United States). (Barnes, 2003; Davis, 2008; Hanna, et al., 2003; Hogg, et al., 2010; Jacobs, Sr., 2006; Jones, 2004; Taylor and Pfannenstiel, 2009)

Physical Description

Yellow sac spiders are typically cream to light yellow in color, sometimes with an orange-brown stripe running lengthwise across the abdomen. While individuals are uniform in base color, their chelicerae, tarsi, and pedipalps are dark brown. The body color is partially determined by their diet; individuals known to feed on house flies are noticeably more gray in color, while those who feed on red-eyed fruit flies take on a reddish tinge, and so forth. Females are slightly larger than males, 5-10 mm and 4-8 mm, respectively. Although females' bodies are slightly larger and more robust, males have a larger leg span. The front pair of legs in particular are longer and are used in capturing prey. (Barnes, 2003; Davis, 2008; Jacobs, Sr., 2006; Jones, 2004)

  • Sexual Dimorphism
  • female larger
  • Range length
    4 to 10 mm
    0.16 to 0.39 in


Mating season is assumed to be during the summer months, due to increasing populations observed during this time. After mating, females produce egg sacs within about 14 days, guarding the eggs and immature spiders for about 17 days, repeating this process multiple times during breeding season. Throughout develpment, yellow sac spiders undergo molting in order to grow, usually from within the protection of their silk sacs. These spiders overwinter as juveniles in the safety of these silk sacs, molting and achieving adulthood in late spring and emerging from the egg sac. (Davis, 2008; Jacobs, Sr., 2006; Jones, 2004)


Males seek out females during breeding season (early summer) and up to 30% of males are killed and eaten by the females after breeding. Females typically mate only once but produce multiple egg sacs (as many as 5, each containing approximately 40 eggs) during June/July; they enclose themselves in the egg sac in order to defend the eggs/young. (Barnes, 2003; Davis, 2008)

Female yellow sac spiders desposit their eggs in loose silk sacs within their webs in June or July, roughly 14 days after mating. They then stay with their young for roughly 17 days. Males and females typically reach maturity at 119 days and 134 days respectively, though time until maturity varies from 65 to 273 days depending on environmental conditions (temperature, humidity, and day length). (Davis, 2008; Jacobs, Sr., 2006; Jones, 2004)

  • Breeding interval
    Breeding occurs once a year, with females depositing eggs 2-5 times during the breeding season.
  • Breeding season
    Late spring to early summer.
  • Average gestation period
    14 days
  • Average time to independence
    17 days
  • Range age at sexual or reproductive maturity (female)
    65 to 273 days
  • Average age at sexual or reproductive maturity (female)
    119 days
  • Range age at sexual or reproductive maturity (male)
    65 to 273 days
  • Average age at sexual or reproductive maturity (male)
    134 days

Females remain in the egg sac for 17 days on average to protect their eggs and young. (Davis, 2008)


There is no currently available information regarding the lifespan of yellow sac spiders.


Yellow sac spiders are nocturnal, spending the day in their nest-like silk sacs and hunting at night. They are most active during the spring and summer and are known to balloon from or create bridges between structures using a strand of silk. Juveniles tend to say in the egg sac during the winter but do venture out in order to feed. These spiders do not rely on webs but instead actively hunt, using their longer front legs in capturing prey. They inject prey with cytotoxic venom using their fangs (part of the chelicerae), beginning the digestive process, then using their sucking stomachs to feed. (Davis, 2008; Jacobs, Sr., 2006; Jones, 2004; Nieuwenhuys, 2008)

Home Range

Localized to the surrounding areas of their silk sacs. (Davis, 2008; Jacobs, Sr., 2006; Jones, 2004)

Communication and Perception

This species has eight simple eyes aligned in two rows of four, consisting of secondary and primary eyes. Secondary eyes are light sensitive and adept at tracking movement. Primary eyes are the only set of movable eyes and are used to view objects within a close proximity. Spiders can dectect touch, vibrations, and smells through various setae connected to their nervous system. (Davis, 2008; Jacobs, Sr., 2006; Jones, 2004; Nieuwenhuys, 2008)

Food Habits

Yellow sac spiders prey upon anthropods such as leafhoppers (Erythroneura variabilis), fleahoppers (Pseudomatoscelis seriatus), fruit flies (Drosophila sp)and cotton plant bugs (Creontiades signatus) as well as eggs of lepidopterans such as Helicoverpa zea and Plutella xylostella. They have also been known to prey on other spiders including Anyphaena pacifica and Theridion melanurum. Aside from their predatory diet, these spiders consume nectar as they forage. Nectar consumption elevates fitness through increased survival, growth, and fecundity, especially during periods of prey scarcity. Incorporation of nectar into the diet can also accelerate sexual maturity and enhance offspring volume. (Durham, et al., 2009; Hanna, et al., 2003; Hogg and Daane, 2011a; Hogg and Daane, 2011b; Jacobs, Sr., 2006; Jones, 2004; Pfannensteil, 2008a; Pfannensteil, 2008b; Silva-Torres, et al., 2010; Taylor and Pfannenstiel, 2009)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • nectar


As these spiders are nocturnal, hiding in their silken sacs during the day, protecting them from predation, there is currently no information available regarding specific predators of this species.

Ecosystem Roles

Yellow sac spiders are secondary consumers and are valuable anti-pest predators in agricultural ecosystems, particularly in vineyards, apple orchards and cotton fields. (Durham, et al., 2009; Hanna, et al., 2003; Hogg and Daane, 2011a; Hogg and Daane, 2011b; Taylor and Pfannenstiel, 2009)

Species Used as Host
  • Information not found.
Mutualist Species
  • Information not found.
Commensal/Parasitic Species
  • Information not found.

Economic Importance for Humans: Positive

These spiders are vital predators of agricultural pests; their presences results in higher crop yields and greater financial gain. (Durham, et al., 2009; Hanna, et al., 2003; Hogg and Daane, 2011a; Hogg and Daane, 2011b; Taylor and Pfannenstiel, 2009)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Yellow sac spiders are regularly found in close proximity to humans, within homes or during outdoor activities. They possess a cytotoxic venom, which can have necrotizing effects. Although necrotic legions are rare, these spiders may be quite aggressive, particularly females defending eggs, and can administer painful bites that may require medical attention. (Davis, 2008; Jacobs, Sr., 2006; Jones, 2004; Smith, et al., 2005)

  • Negative Impacts
  • injures humans
  • household pest

Conservation Status

This species currently has no special conservation status.


Drew Murphy (author), University of Michigan-Ann Arbor, Jeremy Wright (editor), University of Michigan-Ann Arbor.



living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map


living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


living in landscapes dominated by human agriculture.


Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat


uses smells or other chemicals to communicate


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

female parental care

parental care is carried out by females


union of egg and spermatozoan


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body


referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


Having one mate at a time.


having the capacity to move from one place to another.


active during the night


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


living in residential areas on the outskirts of large cities or towns.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


living in cities and large towns, landscapes dominated by human structures and activity.


an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate

young precocial

young are relatively well-developed when born


Bajwa, W., M. Aliniazee. 2001. Spider fauna in apple ecosystem of western Oregon and its field susceptibility to chemical and microbial insecticides. Journal of Economic Entomology, 94/1: 68-75. Accessed February 08, 2012 at

Barnes, J. 2003. "Arthropod Museum Notes: Agrarian Sac Spider" (On-line). Arthropod Museum, Dept. of Entomology, University of Arkansas. Accessed September 19, 2012 at

Costello, M., K. Daane. 2005. Day vs. night sampling for spiders in grape vineyards. Journal of Arachnology, 33/1: 25-32. Accessed February 08, 2012 at

Davis, R. 2008. "Yellow Sac Spiders" (On-line). Accessed March 25, 2012 at

Durham, S., A. Flores, D. Comis. 2009. Working After Hours: A Nighttime View of Insect Predation. Agricultural Research, 57/9: 453-461. Accessed February 08, 2012 at

Furman, D., W. Reeves. 1957. Toxic bite of a spider, Cheiracanthium inclusum Hentz. California medicine, 87/2: 114. Accessed February 08, 2012 at

Hanna, R., F. Zalom, W. Roltsch. 2003. Relative impact of spider predation and cover crop on population dynamics of Erythroneura variabilis in a raisin grape vineyard.. Entomologia Experimentalis et Applicata, 107/3: 177-191. Accessed February 08, 2012 at

Hogg, B., R. Gillespie, K. Daane. 2010. Regional patterns in the invasion success of Cheiracanthium spiders (Miturgidae) in vineyard ecosystems. Biological Invasions, 12/8: 2499-2508. Accessed February 08, 2012 at

Hogg, B., K. Daane. 2011. Diversity and invasion within a predator community: impacts on herbivore suppression. Journal of Applied Ecology, 48/2: 453-461. Accessed February 08, 2012 at

Hogg, B., K. Daane. 2011. Ecosystem services in the face of invasion: the persistence of native and nonnative spiders in an agricultural landscape. Ecological applications, 21/2: 565-576. Accessed February 08, 2012 at

Jacobs, Sr., S. 2006. "Commonly Encountered Pennsylvania Spiders." (On-line). Accessed March 25, 2012 at

Jones, S. 2004. Sac Spiders. Ohio State University Extension Factsheet, 2060A: 1-3.

Leech, R., T. Brown. 1994. The first Alberta record for Cheiracanthium inclusum (Hentz) (Araneida: Clubionidae), with observations on a human bite reaction. Canadian Entomologist, 126/1: 187. Accessed February 02, 2012 at

Nieuwenhuys, E. 2008. "The anatomy of a spider" (On-line). Accessed April 15, 2012 at

Pfannensteil, R. 2008. Development of the Cursorial Spider, Cheiracanthium inclusum (Araneae: Miturgidae), on Eggs of Helicoverpa zea (Lepidoptera: Noctuidae). Journal of Entomological Science, 43/4: 418-422. Accessed September 20, 2012 at

Pfannensteil, R. 2008. Spider predators of lepidopteran eggs in south Texas field crops. Biological Control, 46: 202-208. Accessed September 20, 2012 at

Scientists at University of California publish research in biological invasions., 2010. Biological Invasions; Scientists at University of California publish research in biological invasions. Science Letter: 4788. Accessed February 08, 2012 at

Silva-Torres, C., I. Pontes, J. Torres, R. Barros. 2010. New records of natural enemies of Plutella xylostella (L.) (Lepidoptera: Plutellidae) in Pernambuco, Brazi. Neotropical Entomology, 39/5: 835-838. Accessed September 20, 2012 at

Smith, S., R. Wells, E. Smith, M. Foradori. 2005. Survey for potentially necrotizing spider venoms, with special emphasis on Cheiracanthium mildei. Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 141/1: 32-39. Accessed February 08, 2012 at

Taylor, R., R. Pfannenstiel. 2009. How Dietary Plant Nectar Affects the Survival, Growth, and Fecundity of a Cursorial Spider Cheiracanthium inclusum (Araneae: Miturgidae). Environmental Entomology, 38/5: 1379-1386. Accessed February 08, 2012 at

Vetter, R., G. Isbister, S. Bush, L. Boutin. 2006. Verified bites by yellow sac spiders (Genus cheiracanthium) in the United States and Australia: Where is the necrosis?. American Journal of Tropical Medicine and Hygiene, 74/6: 1043-1048. Accessed February 08, 2012 at