no subject, just verb. For it to be a <em>c</em><em>o</em><em>m</em><em>p</em><em>l</em><em>e</em><em>t</em><em>e</em> sentence, it would need a subject to accomodate the verb.
Complete sentence:
<u>H</u><u>e</u> <u>c</u><u>o</u><u>m</u><u>m</u><u>a</u><u>n</u><u>d</u><u>e</u><u>d</u> the continental army in the revolutionary war.
"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".