All insects have eyes,

but no other organ of sense discernible,
except that some insects have a kind of a tongue corresponding to a
similar organ common to all testaceans; and by this organ such insects
taste and imbibe their food. In some insects this organ is soft; in
other insects it is firm; as it is, by the way, in the purple-fish,
among testaceans. In the horsefly and the gadfly this organ is hard,
and indeed it is hard in most insects. In point of fact, such
insects as have no sting in the rear use this organ as a weapon, (and,
by the way, such insects as are provided with this organ are
unprovided with teeth, with the exception of a few insects); the fly
by a touch can draw blood with this organ, and the gnat can prick or
sting with it.

Certain insects are furnished with prickers or stings. Some
insects have the sting inside, as the bee and the wasp, others
outside, as the scorpion; and, by the way, this is the only insect
furnished with a long tail. And, further, the scorpion is furnished
with claws, as is also the creature resembling a scorpion found within
the pages of books.