Furrow Orb Weaver Spider - Larinioides cornutus
Also commonly called foliate spider, after its prominent folium, or pigmented design on the abdomen.
Family Araneidae - Orb Weavers
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Foliate Spider Female
 mature female above = 12mm, male below =10mm.
Foliate Spider Male
The Orb Weaver Larinioides cornutus, commonly called the furrow, or foliate spider, is very common on human structures, especially under eaves and porches. They live on my back porch by the dozens, males and females alike in their smallish-orb webs.  Unlike their larger sisters amongst the weeds, these beautiful little rascals are strictly nocturnal, hiding in crevices or in foliage retreats from dawn till dusk.

Orb weavers comprise a huge family of spiders, with 3500 species worldwide, 180 of which call North America home. These spiders vary greatly in color, shape and size, measuring between 2 - 30mm (1/16 -- 1 1/4") long. They have eight eyes arranged in two horizontal rows of four eyes each. Orb weaver males are generally much smaller than the females and commonly lack the showy coloring of their fairer sex, but that is not so with this species: the males are only slightly smaller, and have an equally gaudily-decorated abdomen.

Furrow Orb Weaver

This female has captured a queen ant from a nearby swarm. Ants swarm about 2-3 days after a good rain and the whole neighborhood shares in the bounty, especially the spiders. I saw one marbled orbweaver capture dozens of them in an hour.

Her eye is shining because of a membrane called a tapetum lucidum (Latin: "bright tapestry") which is a layer of tissue in the eye of many vertebrates and invertebrates. Lying immediately behind the retina, it reflects visible light back through the retina, increasing the light available to the photoreceptors. The tapetum lucidum contributes to the night vision of many nocturnal animals, especially predators, e.g., cats and spiders [3]. L. cornutus is strictly nocturnal.

Furrow Orb Weaver Spider
This immature female took about 30 seconds to completely wrap a moth
Orb weaving spiders often add stabilimenta to their webs. Stabilimenta are conspicuous lines or spirals of silk, included by many diurnal spiders at the center of their otherwise cryptic webs. It has been shown spider webs using stabilimenta catch, on average, 34% fewer insects than those without. However, webs with the easily-visible markings are damaged far less frequently by birds flying through the web. It is an evolutionary tradeoff the spider can influence every time it builds a new web. The inclusion of stabilimenta is influenced by many factors, including prey density and web location.  -- Behavioral Ecology magazine.

Spider chases cricket
Bossy young L. cornutus (< 5mm) chased away a striped ground cricket by continually attacking its antennae.

References
  1. Bugguide.net, "Furrow Orb Weaver, Larinioides cornutus"
  2. Eric R. Eaton, the Balabans, Lynette Schimming, Jeff Hollenbeck, Chuck Entz, kschnei, Bugguide.net, "Genus Larinioides - Furrow spiders"
  3. Wikipedia, Tapetum lucidum
Wondering how to get that bug identified? Please see the kind folks at Bugguide.net. (North America)
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