care and feeding of the newborn spider

I happened to see a baby spider because it was on top of a piece of furniture that goes to eye level, is white, and hosts a bright lamp. Otherwise it would have been difficult as the spider was very very tiny. Which made me wonder: what do baby spiders eat? Do they spin tiny tiny webs and catch tiny tiny bugs, all so small that you’d never notice? Do they hunt tiny bugs manually sans web? Do they drink spider milk (j/k)?

How do you know it’s a baby spider and not just a particularly small one?

I guess it’s an assumption. Although, I remember reading that baby spiders ‘balloon’ and I saw another tiny spider floating through the air in my bedroom once on a string of silk. But in any case, whether or not my spider was a baby, there are baby spiders, and I’ve never seen a spider web have a spider that small, so what do they eat? And for that matter, what do tiny adult spiders eat?

I don’t know what house spiders eat but, anecdotally, I’m told that such creatures can go for months without food or water.

They eat the same stuff as adult spiders, but smaller. I just noticed the first color changed garden spider for the year. It was a dark yellow in the sunflower. They regularly kill and eat insects much larger than themselves.

As Harmonious Discord said, spiders will tackle comparatively huge prey. They are amongst the few predators that will individually take on prey may times larger than themselves.

As for webs, many small spider species and the young of many larger web weaving spiders don’t use their webs for catching prey per se because at those sorts of scales they aren’t effective. Instead the web acts as somewhere for the spider to hide as well as having an extension of ‘tripwires’ to detect prey landing nearby. The spider then rushes out and attacks the prey rather than waiting for it to entangle itself.

As for you never having seen spiders that small, that’s probably true, but you have almost certainly seen evidence of them. When you look at a lawn carefully or field on a dewy morning you will often notice literally thousands of these tiny webs, covered in dew and coating almost every available surface. Yet I bet you have never seen a tiny spider in those webs. That is because, as you said in your first post, without ideal lighting and contrast the things are so small they are scarcely visible and few people take the time to look carefully. But if you care to take the effort you can easily peel back those tiny webs and there you will see the tiny spiders that made them, ranging in size from a quarter of an inch down to spiders about >>>>> . <<<<< that small.
A sit-and-wait tactic might seem weak, but there are so many tiny insects out there that several will certainly land on every square inch of exposed surface every day. A small spider can make a comfortable living in this manner, and once they have grown large enough they can move on to larger prey and begin constructing more functional webs.

Look in the petals of flowers for a lurking spider. They like to wait where the hunting is good.

I found a bunch of baby spiders once weaving tiny orb webs about the diameter of tennis balls (the webs, not the spiders). The strands of the webs were about 1/16th of an inch apart. Amazingly delicate and intricate.

So, yes.