Funnily enough I'm reading a book right now with animal people and they eat super sized bugs for their protein. Like some breeds of Beetle are the size of an Ox.

There was also an incident concerning a Centipede that was so big it could wrap itself around the pipes running along the ceiling of the factory it inhabited and still have plenty of length to dangle down and eat people on the floor.

I can't even stand Centipedes an inch long, so I'm not sure how I'd feel about one the length of a train.