Feeding my spider flies?

Question

I live in Tijuana, Mexico and 4 days ago i caught a small black spider about a bit bigger than the average fly. Its in a jar, it already strung a web and i threw in a smaller spider and it ate it. I was wondering if i can give it dead flies?

His jar has some soil, 2 small rocks and a stick.

Im not sure what species the spider is, i lifted up a rock and I found it. As stated before its bigger than the average fly and it is all black with tannish/yellowish dots and a mouth-like drawing on its back.

here is a sucky picture i drew on microsoft paint

http://i76.photobucket.com/albums/j22/SVRMASTER/myspider.jpg

Answer 1

I am not sure what kind of spider it is, but I would feed it small feeder crickets bought at a pet shop.  The biggest concern is that wild caught bugs could contain parasites or pesticides.  

To identify the spider, I would need more info.  What kind of web did it make?  Was it a flat, thick sheet like web or a tall cobweb on the stick you put in?

Add details - That looks like a cobweb spider, family Theridiidae, possibly of the Steatoda genus.  It is also possible that it is a species of widow spider.

Answer 2

I'd suggest not feeding it dead insects at all.  Spiders eat the insides of the insect and the best way to do this is to inject them while the bug is still alive.