For example we notice Peterson First Guide to Caterpillars of North America (1998), where we learn the "stages between moltings are called instars: a caterpillar will go through several before it reaches full size in its final instar. This mature larva may bear little resemblance to its first instar." Although it is not typical used this way, the adult stage of an insect may also be called an instar.
Peterson First Guide to Mammals of North America, (1998) where we learn: Cats have shorter faces than most dogs do. with smaller ears. Unlike dogs. they have retractile claws. Their tails. whether short or long. are relatively thin. not bushy. Their vision is excellent. Most hunt at night.
Houghton Mifflin tell us:
Paul Ehrlich described Roger Tory Peterson as the "inventor of the modern field guide.”