Explanation

You are told that solider ants guard the colony and supply it with food, thus acting as both _________ and laborers. In this sentence pattern, the first blank (sentries, or “guards”) matches up with “guard the colony” and “laborers” matches up with “supply it with food.”

You know that the queen can continually populate the colony, so fecund (fertile) goes in the second blank and progeny (offspring) goes in the third.

Sentries, fecund, progeny.