The hardened, 30 year-old domestic terrorists of today were twelve years-old when Harry Potter's Chamber of Secrets came out and the scene where spiders chased Harry and Weasly gave them nightmares for MONTHS.
Since no self-respecting dog can be asked to chase scum, we must find other devices.
1:12 Radio Controlled vehicles can be had for about $100. Adding sound costs a bit more.
Enjoy the mental picture.