If you've ever hiked in August then I'll bet you've walked through the web of this spiked spider. Now that I've looked at one of these nasty-looking critters up close, I'm going to be paying closer attention to where I'm going. If it makes you feel better, these spiders are actually helpful in catching gnats and mosquitoes. The female Spined Micrathena (above) has 10 spikes and prefers open, shady areas to construct her web. She builds a new web each day at dawn three to seven feet off the ground -- and then when the sun sets she ingests nearly every strand. The male of the species is much less interesting -- he doesn't weave a web and is only a fraction of the size of the female.