They wiggle like crazy which excites and entices herps. Great food for a picky eater!
They taste good (a guess, but herps greedily consume them)
Come in four sizes to satisfy most pets, from darts to dragons
Stimulate the appetite of animals that don't readily feed
Can halt or reverse the effects of metabolic bone disease
Provide a boost of nutrition for gravid or just-laid females 
A great start for all hatchlings!