For example, his sermon to the doves, beginning, "My little sisters, the doves," in which he reminds them that their form is the emblem or symbol of the Holy Ghost, is a beautiful poem; and has been, with many others, translated into nearly all modern languages.

But observe that neither St.Francis nor any other saint has anything to say on the subject of insects.
Perhaps we must go back further than Christianity to guess the meaning of these distinctions.

Among the ancient races of Asia, where the Jewish faith arose, there were strange and sinister beliefs about insects--old Assyrian superstitions, old Babylonian beliefs.

Insects seemed to those early peoples very mysterious creatures (which they really are); and it appears to have been thought that they had a close relation to the world of demons and evil spirits.

I suppose you know that the name of one of their gods, Beelzebub, signifies the Lord of Flies.