Orb Weaving Spiders: Araneidae

While Araneidae species may rank among the most easily recognized group of spiders in the world, common knowledge about Araneidae just about stops with those facts.

Stopping there would be a mistake. Knowing about genera and species diversity within the family may not make for interesting bedtime reading, except at Halloween, but it does make for some interesting spider facts.

First up, all Araneidae do not spin webs. Spiders in the genus mastophora, commonly called bolas spiders, did not receive the Araneidae web spinning memo. Instead, they use a spun silk line to catch their favorite moth prey.

Recent research suggests that the Araneidae family dates back to the Jurassic Era (206-144 million years ago). From then to now, Arachnologists and spider enthusiasts have documented 2847 Araneidae species, placed withing 167 genera. Taken together, the family "ranks third (out of 110) in terms of number of described spider species.

The The Journal of Arachnology recently published a key to "Genera of Arenid Orbweavers of the Americas" saying, there are 65 genera and about 1,500 different species found from South America, north to Canada.

North America hosts approximately 30 genera and 165 Araneidae species, with 19 genera and 62 species native to Canada.

On many occasions, backyard orbweaver populations consist of colorful, multishaped spiders. The picture at the top of the page, for example, show two species with pointed or arrow shaped bodies.

The first spider shows an Arrow-shaped Micrathena (Micrathena sagittata), a small, one-half inch spider that inhabits eastern forests, fields and residential areas.

The second spider, the Arrowhead Spider (Verrucosa arenata) represents the North American Verrucosa population, and it also inhabits eastern forests and fields.

Unlike other orb weaving spiders, Arrowhead spiders rest on their webs heads up. Most other orb weavers rest head down.

Larinia, a small genus of orb weavers in the United States, gets recognized by their body stripes. Picture two highlights the large dark spots next to the stripes.

Some Larinia directa have small black spots next to the stripes, so regional differences could account for the larger spots on this specimen.

The identification is tentative.

Furrow spiders (genus Larinioides) generally live in habitat near water.

Unlike the more common Araneus species, they are nocturnal hunters. Seeing them in their web during the day is unusual.

Eriophora, a genera of tropical orbweavers also find homes among the branches of southern North America environments.

According to Levi, the native Eriophora population consists of two native species, Eriophora ravilla, with a large presence in Florida and the Lower Rio Grande Valley of Texas, and Eriophora edax, with a smaller presence in the south Texas and the southern areas of Arizona and California.

Both species are described as having a pointed abdomen (with various colors) and banded legs.

While no single picture can serve as positive identification, picture two shows a specimen with a green patch on the abdomen, most probably E. Ravilla.

The bottom picture shows an all reddish specimen that highlights the pointed reddish-brown abdomen with white hairs and banded legs. The identification of Eriophora is tentative.

Eriophora species tend to be night hunters, building their webs at night and retreating to rest on leafs during the day. Their webs are fairly sturdy. Levi provides a picture of a Eriophora fulitginea web that trapped a bat.

© 2005-2013 Patricia A. Michaels