Micrathena gracilis

Distinguished from other Micrathena species by the specific arrangement of abdominal spines—M. gracilis typically shows five pairs of spines with the posterior pair longest and directed rearward. Differs from M. sagittata (Arrowshaped Micrathena), which has a triangular abdomen with three posterior spines forming an arrow shape. Males can be confused with other small orb-weavers but lack the spines characteristic of females. Web structure helps identification: tightly coiled spiral with open hub, often with vague stabilimentum above center.

Small orb-weaving spider with females measuring approximately 8-10 mm in body length. Females possess a hardened, spiny abdomen with prominent pointed projections—typically five pairs of spines arranged symmetrically. The abdomen is usually white, yellow, or pale with variable dark markings. Males are smaller (4-5 mm), lack abdominal spines entirely, and have a more slender, unadorned abdomen. Legs are relatively long and slender. Spinnerets are centrally located on the ventral abdomen rather than posteriorly positioned.

Deciduous forests and wooded areas; mesic (moist) sites with dense shrub vegetation and higher humidity. Prefers areas with greater structural complexity and avoids xeric (dry) sites with open canopy. Webs constructed in understory vegetation, shrubs, and forest edges, typically 2-4 feet above ground. Favors locations with dense vegetation cover and moderate shade.

North America and Central America; recorded from United States (eastern deciduous forests, including Maryland, Ohio, Kansas, Massachusetts), Mexico, and Central America. Distribution extends from Maine to Florida and west to Nebraska and Texas in the United States, with higher abundance in southern portions of range.

Adults active primarily July through September; mature spiders most visible during late summer and early autumn. Overwinters as eggs in silken sacs. Spiderlings emerge in spring.

Flying and jumping insects intercepted in orb web. Documented prey includes leafhoppers, flies, small wasps, bees, and beetles. Unlike many orb-weavers, does not wrap captured prey in silk.

Mated females construct spherical, fluffy white egg sacs approximately 12 mm in diameter containing roughly 90 eggs. Egg sac is the overwintering stage. Spiderlings emerge from eggs in spring, develop through summer, reaching maturity by late July-September.

Builds circular orb webs 20-30 cm in diameter with tight spiral and open hub. Web orientation varies with microhabitat: spiders in shaded closed microhabitats face predominantly north-south, while those in well-lit open microhabitats face east-west. This orientation functions as behavioral thermoregulation, optimizing solar radiation exposure and body temperature. Spider hangs at hub using silk strands from centrally-placed spinnerets; can drop into leaf litter when threatened and reel back when danger passes. Web often tilted between vertical and horizontal planes. Constructs vague stabilimentum (zigzag silk band) above web center, function debated.

Predator of small flying and jumping insects; contributes to regulation of leafhopper and other herbivorous insect populations in forest understory communities. Web-building activity may influence local insect movement patterns. Serves as prey for birds and other arthropod predators.

Completely harmless to humans; does not bite. Occasionally enters homes on vegetation but is an outdoor species that does not survive well indoors. Egg sacs may inadvertently enter homes on Christmas trees or greenery; recommended to place outdoors if found. Provides natural pest control in gardens and wooded areas.

• Micrathena sagittataAlso has spiny abdomen, but with triangular shape and three posterior spines forming distinct arrow shape; web structure similar but abdominal morphology clearly different
• Gasteracantha cancriformisAnother spiny orb-weaver with crab-like spiny abdomen, but has much broader, flattened abdomen with red or white coloration and different spine arrangement; more tropical distribution

None documented in available sources

• orb-weaver
• spiny abdomen
• thermoregulation
• forest spider
• harmless

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Grasshopper Collections and Survey
• Bug Eric: Services
• Tinsel, the Christmas spider and other arthropods that decorate your holiday tree — Bug of the Week
• Bug Eric: Arrowshaped Micrathena spider
• Bichos Argentinos #2 – Pseudomyrmex sp. | Beetles In The Bush
• Traffic Jam Treehoppers | Beetles In The Bush
• Macrohabitat Selection by theOrb Weaving Spider, Micrathena Gracilis
• Web Orientation in the Spider Micrathena Gracilis (Araneae: Araneidae)