"of insects" is an adjective phrase because it's a prepositional phrase that acts as an adjective. It modifies the word "group"; In other words, "of insects" is used to describe the word "group".
Strong A3H7U2F8!
Moderate Secretluvr1
Weak Star1234
I’m sorry but without the text I can’t answer the question I don’t know what info is there so I can’t answer without a risk