bird louse vs insect

bird louse and insect both are nouns.

Word	Noun	Adjective	Verb	Adverb
bird louse	Yes	No	No	No
insect	Yes	No	No	No

As nouns, insect is a hypernym of bird louse; that is, insect is a word with a broader meaning than bird louse:

bird louse: wingless insect with mouth parts adapted for biting; mostly parasitic on birds
insect: small air-breathing arthropod

bird louse (noun)	insect (noun)
wingless insect with mouth parts adapted for biting; mostly parasitic on birds	small air-breathing arthropod
	a person who has a nasty or unethical character undeserving of respect