This was actually drawn years before Red Spiders
This is the second comic in the Red Spiders series, published just over 2 months after the first one. Like its predecessor, it is more of a sketch than a comic. The titular spiders appear to be ascending —or possibly building— a structure, probably to get into the window at the top of the picture. Two spiders at the top appear to be passing a block between them, implying that they are, at least, trying to change the structure.
In the title text, Randall says the comic was drawn years before the previous Red Spiders despite being posted later.
The full series of Red Spiders comics:
- 8: Red Spiders, the first one.
- 43: Red Spiders 2, this one.
- 47: Counter-Red Spiders, in which the humans begin a counter-offensive.
- 126: Red Spiders Cometh, in which the spiders attack a city.
- 427: Bad Timing, in which, in a style more typical to xkcd, the spiders attack a couple in the middle of a serious relationship discussion in a hot-air balloon.
- 442: xkcd Loves the Discovery Channel, in which it appears briefly in the 14th panel crawling over a cube.