You gave me an idea
drop them from a bomb containing a nutritious protein based jelly filled with eggs
the jelly will spread above a field and because it does not weigh that much + acts like jelly acts it wont penetrate the ground that deep and keep the eggs alive
and locusts can live basically anywhere, its just that in Africa they have the food to grow to large populations (we have that already because we manufactured them) plus the locusts that live there are a species that is known to swarm faster.
basically, splice African and European locusts, and alter them so they wont go out of swarm mode, make billions of eggs, put eggs in jelly and shell the enemy farms with the jelly.