Miniature spiders - the brown orbs in the background are the cocoons they hatched from. The cocoons are about half a centimeter in diameter - this gives you an idea how tiny the spiderlings are (half a millimeter according to what I've measured). They're just black dots in the webbing to the naked eye, so I find it interesting to see just how colorful they actually are with many of them having green and blue spots.
The common American house spider, close up and personal. They love my basement apparently and as long as they stay out of reach of curious kitty paws they are doing quite well down there, too. This is a female and she had a whole nursery full of tiny spiderlings close by.
Another spider hatching in the basement! If you compare this to the earlier picture you'll notice that there were three cocoons and now there's four. Momma spider is being pretty reproductive!This is the Common House Spider, Parasteatoda tepidariorum, weaving their cob webs in the homes of many Americans in the US. My basement seems to be a particularly suitable habitat for them apparently. They are completely harmless for humans or pets, unless of course you consider the other bugs in your house "pets" rather than pests. There's often an impressive graveyard of insect carnage accumulating under a female's web over time. Another indication that there is an inhabited web above are little black dots - presumably spider excretions - on the surface below.The adult females can live for over a year. Each female can produce more than 15 egg sacs over her lifetime, each of them hatching hundreds of baby spiderlings. The babies stay in their momma's web for a few days before moving out. At any given time, I can probably find at least 10 females in their webs, tending to dozens of egg cocoons, often with one or two clouds of freshly hatched spiderlings visible. Many of the mature females will have 4-5 cocoons in their webs at one time if you leave them undisturbed for a while. That probably means there are thousands of these spiders spread out over my basement.
Parasteatoda tepidariorum (formerly known as Achaearanea tepidariorum) - the American House Spider. You can tell it is a male from the much smaller size compared to the female and the enlarged pedipalps (aka "boxing gloves") which serve as male sex organs in spiders. The male inserts these on the underside of the female during mating to transfer sperm. If the male is "lucky" they may break off during the process, thus blocking other males from mating with the same female and allowing him to make a quick escape. If he can't get away quickly enough, he may just become the female's next snack. Either way, male spiders often only get a chance to mate once in their life time. He was nervously feeling his way around a female's web, but in the end he was a coward and ran away.
A closer view of the underside of the thorax of a male Parasteatoda tepidariorum. You can tell this is an adult male ready to mate from the swollen "boxing glove" appearance of his pedipalps. Mature male spiders will transfer sperm from glands on their abdomen into these and store it there for mating. There seems to be some sort of hook at their ends. During mating, the male inserts these into two openings of the epigyne on the underside of the female's abdomen and uses them like syringes to inject the sperm into the female.
A closer view of the underside of a mature female Parasteatoda tepidariorum. You can see her two lungs as well as the epigyne (pouch for sperm insertion during mating). I'm no spider expert, but I'm being told that these structures can aid in species identification, so I tried to get a close-up. The spiders conveniently love to hang upside down in their webs, so getting a "belly shot" is actually rather easy if you find a web in a lower location. This female had a big egg sac in her web, so she certainly has mated before and maybe even recently as there were two males close by acting very interested.