Mecaphesa celer

Females are readily distinguished from similar Mecaphesa species by their large, round abdomens and coloration. Males are difficult to identify from Mecaphesa dubia and Mecaphesa rothi due to similar appearance; distinguishing these three species requires careful examination and may be complicated by natural intraspecific variation. The combination of red leg bands, white abdomen with V-shaped brown spots, and dark setae in males is characteristic but not definitive without comparison to related species.

Adults display strong sexual dimorphism in both size and coloration. Females are dramatically larger than males, with body mass often exceeding ten times that of males. Females have large, round abdomens much larger than their heads and occur in three color variants: bright solid yellow with minimal brown spotting; yellow with reddish-brown abdominal streaking; or completely white with dull brown streaking. Males are roughly half the female size, with abdomens and heads approximately equal in size. Mature males are often darker than females and possess distinctive red bands on their legs, whiter abdomens with four or more pairs of brown spots forming a V-shape from mid-abdomen to the end, and noticeable dark setae covering the body. All individuals have characteristically long first two pairs of legs and short back two pairs of legs typical of Thomisidae.

Occupies flowers and upper parts of plants, including shrubs, bushes, and small trees. Frequently found on crop plants such as sorghum, cotton, and alfalfa. In agricultural settings, has been recorded as comprising 5.3% of spider collections in Eastern Texas cotton fields. Also inhabits fragmented volcanic habitats with isolated vegetated patches surrounded by barren matrix, as demonstrated by populations at Craters of the Moon in Idaho.

Widely distributed across North and Central America. Nearctic distribution spanning the North American continent. Specific records include Alberta and British Columbia in Canada, and documented populations at Craters of the Moon National Monument and Preserve in Idaho, USA.

Preys upon insects visiting flowers, including pollinating insects. Specific prey items documented include aphids and other potential agricultural pests. Does not use webs for prey capture.

Spins webs only for egg sac construction and mating purposes, not for hunting. Juvenile dispersal occurs and appears sufficient to maintain gene flow across fragmented habitats.

Sit-and-wait predator that ambushes prey from flowers and upper plant stalks. Uses elongated front legs to seize prey. Males perform courtship behavior involving abdominal vibration, slow approach with leg and pedipalp gesturing, and touching the female with front legs. Receptive females respond by raising legs and suspending themselves in silk threads. Copulation lasts approximately 3 to 10 minutes, with the male remaining on the female until she becomes active. Females exhibit sexual cannibalism, killing and consuming males that remain in proximity after copulation.

Serves as a biological control agent in agricultural systems by preying on insect pests of crops. In sorghum, cotton, and alfalfa, hunts in the upper plant parts where grains or harvested products develop, protecting against pests such as aphids. Trapped insect carrion on sticky plants may enhance indirect defense by attracting predatory arthropods, though this specific interaction has been documented for related crab spiders in similar systems.

Valued as a natural pest control agent in agriculture. Provides protection for sorghum, cotton, and alfalfa crops by reducing herbivore damage. Formerly classified under genus Misumenops, with older literature using the synonym Misumenops celer.

• Mecaphesa dubiaMales appear quite similar to M. celer males, making visual identification difficult due to overlapping morphological traits
• Mecaphesa rothiMales closely resemble M. celer males; distinguishing between these three species requires careful examination and is complicated by natural intraspecific variation
• Mecaphesa asperataCongeneric crab spider with similar hunting behavior on flowers, but distinct in appearance and distribution

• crab spider
• Thomisidae
• sexual dimorphism
• sexual cannibalism
• biological control
• agricultural pest control
• sit-and-wait predator
• flower-dwelling
• panmixia
• Nearctic

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• Bring on the Tourists! | Bug Squad
• Day hike at Little Lost Creek Conservation Area | Beetles In The Bush
• 🌿 Botanizing w/ the WGNSS Botany Group at Victoria Glades Preserve | Beetles In The Bush
• Panmixia in spiders ( Mecaphesa celer , Thomisidae) despite fragmented habitat at Craters of the Moon in Idaho