I know this might not be popular but whatever, you guys need to hear the truth.
Primarily, capitalism is a social activity. Spiders and other arachnids are not social animals. So how are they supposed to use media of exchange and develop division of labor? Its not going to happen in my lifetime, so thats out.
Secondarily, I cannot effectively communicate with spiders, Charlotte’s Web notwithstanding. So how could we develop prices without being able to bid on products and services? Impossible.
Tertiarily, I dont have much demand for spider products. Humans already sell silk and bugs. While the silk might be produced through what one would consider a form of slavery, I actually dont own any silk products (except for some underwear, and the pockets in my best suit. Edited to add, and about two dozen ties, and a few pocket squares and hankerchiefs.). So I dont think other people will demand spider products when they could easily fill those needs from human sources, and this creates a significant barrier to entry into the market for all arachnids.
Quaterniarily, I dont think spiders need much of what humans like me produce either. So there is significant expense associated with creating the means to produce things that spiders might buy. And remember, they have no known means of paying for these products anyway. So I think it would be a malinvestment.
Based on these arguments I think that Arachno-Capitalism is doomed to fail despite what any keyboard warriors might think or say. So have at it.