Spiders vary widely in appearance and habits. Some weave flat, vertical webs, while others weave spherical or funnel-shaped webs. Still others don't weave webs at all and actively hunt their prey. As arachnids, all spiders have eight legs and multiple eyes, usually five. However only a small number of common spiders have legs that are red or some variation of the colour.
Marbled Orb Weaver
With more than 1,500 species found worldwide, the orb weavers are the largest genera of spiders on earth. The marbled orb weaver (Araneus marmoreus) has distinctive colouration, with a large abdomen of orange or yellow with geometric black or brown lines. The medium-length legs are bright red at the thorax and end in wide black-and-white bands. These spiders are harmless to humans.
Woodlouse Killer or Woodlouse Hunter
The sowbug killer (Dysdera crocata). This fearsome-looking spider has a glossy body and large, powerful mandibles that allow it to bite through the carapace of woodlice (also called woodlouse or pill bugs). The body is about three-quarters inches long, with an elongated muddy, light grey abdomen, dark reddish-orange thorax and legs of a similar colour at the thorax but fading to orange near the ends. Despite their appearance, they are harmless to humans.
Also called the violin spider or fiddleback because of the violinlike marking on the top of its cephalothorax (fused head and thorax). The entire spider is a greyish-brown colour, but the long, thin legs are muddy reddish-brown. Short, velvety hairs cover the entire body. Both males and females are venomous, and while a bite rarely kills humans, it can cause tissue necrosis --- the death of skin and muscles cells that can cause severe pain and disfigurement.
Cross or European Garden Spider
This is one of the most common garden spiders. Growing nearly a couple of cms (inch) in length --- and with very long legs usually grouped together in pairs, giving a crosslike appearance. Some are banded, striped or have blotches of colour, but the colours are most often orange, yellow, white and brown. The banded legs contain yellow or white, brown and rust stripes, and these spiders create large, very strong webs to snare their victims.
These small arachnids are one of the most colourful and strange-looking spiders. The spiny ridges on the abdomen of the females may be nature's way of warding off predators. The arrow-shaped Micrathena (Micrathena sagittata) belongs to the orb weaver species and is harmless to humans. The elongated, inverted V-shaped abdomen features two backward-facing prominences that look like stingers but are not. The top of the abdomen has large splotches of white and the rest of the spider, including the legs, is a rust-red colour.
- Colorado State University; Spiders in the Home; F.B. Peairs, et al.; December 2008
- Penn State University: Marbled Orb Weaver Spider
- Bug Guide: Woodlouse Hunter Spider
- Ohio State University; Brown Recluse Spider; Susan C. Jones
- Wohill; Cross-spider (Araneus diadematus); Jan Nippe Karlsson; June 22, 2008
- Insect Identification: Arrow-Shaped Micrathena Spider