Ok. The Hunting Spiders are indeed units of 2-4. So here is a revised 1000 pt. Spider army:
Units #1, 2, and 3.
4 Hunting Spiders
Novice Shaman w/ Gourd Bombs
1 Blowpiper Leader
Shaman on Drone with Fleetness, Chant, and Seeds of the Poison Yukka
Total: 991 points
For a variation, and to keep with the spider theme, you can drop the Blowpipers, and add a unit of 7 Webmasters, and 1 Leader, for a new total of 997 points.
The basic principle remains the same. The spiders are, of course, the main attack units. I gave each spider unit a Novice Shaman, as opposed to the Webmaster Leader, to give them the Gourd Bombs, to have some sort of ranged attack, albeit a short ranged one. Seeing as how the Shaman can only throw the Gourd Bombs 5", the Powder Pipe seems to be equally useful, as I'd hate to see my Bomb deviate onto my own spiders...that would be most un-spiffy.
The Blowpipers are mainly a harassing unit, to slow down the enemy advance, and occupy their attention while the spiders advance. Even still, with such large numbers of darts flying through the air, you're going to make kills, just by sheer volume.
The Shaman on Drone, as before, is there to support and augment the spiders, and as a harasser, tossing Yukka seeds, engaging light troops, and general disruption and drawing as much fire away from the spiders as possible.
Hope you like it!