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Genus Micrathena

Arrow-shaped Micrathena - Micrathena sagittata - female arrow spider??? - Micrathena sagittata Green and red spider - Micrathena sagittata ??? - Micrathena sagittata I believe Micrathena sagittata - Micrathena sagittata spider - Micrathena sagittata very strange spider - Micrathena gracilis Araneidae, Spined Micrathena - Micrathena gracilis
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynes )
Family Araneidae (Orb Weavers)
Genus Micrathena
Other Common Names
Spiny Orbweaver
Explanation of Names
Author of name: Sundevall, 1833
Gender: Feminine

From the Greek adjective for "small" and the name of the goddess Athena, patroness of domestic arts and handicrafts, especially spinning and weaving.(1)
4 species in BugGuide's range (North America north of Mexico)
Body length: 3.0-5.9 mm (males) & 4.7-10.8 mm (females)(2)
funebris female:

gracilis female: male:

mitrata female: male:

sagittata female: male:
funebris - southern Arizona and southern California south to Costa Rica.(3)
gracilis - (eastern U.S.) central Wisconsin to southern New Hampshire and south to Panama.(2)
mitrata - (eastern U.S.) Wisconsin to Maine and south to Panama.(2)
sagittata - (eastern U.S.) central Minnesota to New Hampshire and south to Costa Rica.(2)

The only Micrathena recorded from Canada, as of 2010, is M. sagittata in Ontario, according to the monograph by Paquin et al. 2010 (Checklist of the spiders (Araneae) of Canada and Alaska. Zootaxa 2461: 1–170).
Life Cycle
Females place eggs in a fluffy egg sac on vegetation near the web. Young Micrathena look much different than the adults.
These are diurnal (daytime active) spiders that build vertical, orb-shaped webs.

Micrathena are different from most araneids in that they first bite their prey, then wrap it. Most other orbweavers wrap it first, then bite.

Males are not very commonly collected with the females; they are easier to find by sweep-netting at night.
Print References
Dondale, C.D., J.H. Redner, P, Paquin and H.W. Levi, 2003. The Insects and Arachnids of Canada Part 23: The Orb-weaving Spiders of Canada and Alaska, NRC Research Press 141-150. [BugGuide entry here and google preview available here]

Levi, H.W., 1985. The spiny orb-weaver genera Micrathena and Chaetacis (Araneae: Araneidae). Bull. Mus. Comp. Zool. Harv. 150(8): 429-618. [available online from here]

Bukowski, T. & T. Christenson, 1997. Natural history and copulatory behavior of the spiny orbweaving spider Micrathena gracilis (Araneae, Araneidae). Journal of Arachnology 25(3):307–320. [available online here]
Internet References
Works Cited
1.Spiders of North America: An Identification Manual
D. Ubick, P. Paquin, P.E. Cushing and V. Roth (eds). 2005. American Arachnological Society.
2.The Orb-weaving Spiders of Canada and Alaska - The Insects and Arachnids of Canada Part 23
Dondale, C.D., J.H. Redner, P, Paquin and H.W. Levi. 2003. NRC Research Press.
3.The spiny orb-weaver genera Micrathena and Chaetacis (Araneae: Araneidae)
Herbert Levi. 1985. Bulletin Museum of Comparative Zoology Harvard 150(8): 429-618.