I got them to peg on their bugs then peg their spiders somewhere else on the web. Then we got the spiders to run along the web till they got to their bugs to eat them! (The original post idea had the spiders rescuing bugs so you could go for that instead). Lots of fun! Bud was brilliant at it, Champ got a little overexcited and started to run into the string a bit so we cut this short after a while, but it was great fun while it lasted.
Even better I put the string laminated bugs and spiders and the pegs in a box so we can pull it out at anytime.