Many species of spider are generically referred to as “house spiders,” especially by homeowners who commonly encounter brown or gray arachnids scuttling about floor edges or ensconced in wispy ceiling-corner webs. If “house spider” is referencing spiders often entering homes, they can be any of several different species — from the roaming wolf spiders that chase down prey, to the cobweb spiders that wait for their web strands to ensnare victims. Most house spiders are harmless to humans and valuable as pest control. They can be prolific egg layers.
TL;DR (Too Long; Didn't Read)
Species of spiders that tend to enter homes are capable of laying hundreds of eggs at one time. There may be more than 200 eggs in an egg sac and some spiders may lay nine of these sacs.
Spiders in general have the capacity to lay hundreds of eggs at a time. Female “house” or “cobweb” spiders of the family Therididae may deposit more than 200 eggs in their egg sacs; with multiple fertilizations, they may lay nine such egg parcels, according to the University of Rhode Island. Female spiders typically affix these silken egg sacs somewhere in their web (if a web-building species) or physically tote them around.
Wolf Spider Eggs
Wolf spiders are active, fast-moving and relatively large spiders that often enter homes — particularly in late summer or autumn in response to cooling temperatures. Female wolf spiders care for their offspring in an interesting manner. They carry the egg sacs with them, attached beneath their abdomen. When the eggs hatch, the baby spiders — called “spiderlings” — migrate to the adult’s back and remain there for days or even weeks.
Found throughout much of the world and commonly encountered in airy webs in basements and dimly lit room corners, the cellar spider — sometimes called the "daddy longlegs" spider — demonstrates another method of egg care. These slender, extremely long-legged spiders may lay 20 to 30 eggs per cocoon. The mother carries her egg bundle, then the hatched babies, around in her jaws. The University of Michigan's Animal Diversity Web says the mother typically cares for its spiderlings for nine days after they have hatched.
Jumping spiders are familiar to homeowners as species that stalk their prey on exterior walls or sunny windowsills. The zebra jumping spider is one of the most widespread in the Northern Hemisphere. The female lays some 30 eggs in a single cocoon after an elaborate mating ritual: The male jumping spider signals to the female with its front legs in an attempt to convince her of his intentions — and to show that he isn't insect prey. If successful, he transfers sperm to her reproductive organ via appendages called pedipalps.
About the Author
Ethan Shaw is an independent naturalist and freelance outdoors/nature writer based in Oregon. He holds a B.S. in Wildlife Ecology and a graduate certificate in G.I.S. from the University of Wisconsin-Madison. His primary interests from both a fieldwork and writing perspective include landscape ecology, geomorphology, the classification of ecosystems, biogeography, wildlife/habitat relationships, and historical ecology. He’s written for a variety of outlets, including Earth Touch News, RootsRated, Backpacker, Terrain.org, and Atlas Obscura, and is presently working on a field guide.