The filmy dome spider is one of the most abundant woodland spiders in Missouri. Although the spider is tiny, its snare web, which looks like an upside-down silk bowl, is conspicuous throughout the year. The carapace (head) of this spider is marked with a broad, dark brown middle band with white outer margins. The yellowish-white abdomen is wide and high at the back end, with distinctive mottled brown markings.
Length: between ⅛ and ¼ of an inch (not counting legs).
Habitat and Conservation
Commonly found in woodlands and woodland edges and in dense, low vegetation around houses. The webs are abundant in rock outcroppings, walls, wood piles, and low, dense brush in woodlands. They are rarely found in open areas.
Tiny predators eat tiny prey. This species eats small insects, such as mosquitoes and gnats, that get caught in their webs. The web is positioned horizontally, and the spider rests on the underside of the web. When an insect lands on the web, the spider quickly tears a hole in the web from beneath and pulls the insect down and ties it up. Hiding under the web helps the spider to avoid predation.
As a general rule, spiders in our area hatch from eggs in spring and spend the growing season eating, maturing, mating, and laying eggs. Females are capable of creating webs; males are not. Females continue creating egg cases as long as the weather holds out. As temperatures cool in fall, their metabolism slows, and they generally die when it freezes. Egg cases overwinter, and spiderlings hatch in spring.
It would be easy to dismiss the importance of these tiny predators, but once you have been plagued by the tiny insects they prey on, such as gnats and mosquitoes, you become thankful for their role in limiting such insects.
Spiders are little predators that help to control populations of the insects they capture. Being small themselves, they easily fall prey to larger predators such as birds, reptiles, and mammals. Many animals eat their eggs. Hummingbirds steal webs from spiders in order to build their own nests.