Female Micrathena gracilis are easily recognized by their bulky, striped or mottled abdomen adorned with five pairs of black-tipped spines. They are usually about 1 cm long. This species is sexually dimorphic. Males are much smaller than females, and their abdomen is long and flat and lacks prominent spines.
The Spined Micrathena lives in dense deciduous forests in eastern North America and Central America. Females construct a web in large open spaces in the understory. The web is two-dimensional with a sticky, densely woven spiral (Uetz & Hartsock 1987). It is used to trap flying insects. Flies (Diptera) are the most common prey (Uetz 1990, Uetz & Harstock 1987).
Mature males do not build webs (Bukowski & Christenson 1997, Hodge 1987). They visit females in their webs to mate. Sexual cannibalism appears to be rare in this species and has been observed only when two males courted a female simultaneously (Bukowski & Christenson 2000)
