Actually, in my game the spell was bombastically named "Octavia's one hundred legions" and it's designed as:
Base 5, Touch +1, Sun +2, Group +2, Rego Requisite +1 -> Cr(Re) An 35.
The original spell had the wasps erupt from the caster's mouth. Since the Base Individual for Animal is the size of a pony, which should be at least 50.000 wasps, the basic Group size makes the swarm half a million strong, so you do not need any modifier for size even if you want to work on a relatively massive scale like surrounding an entire village or a small army. The duration could be cut down to Concentration, saving 5 levels, but I think this way it's much more practical. The Rego requisite allows you to give the wasps one (even reasonably complex) command when creating them - forming a wall around a space and guarding it against intrusion is a very reasonable one. Foraging for food is another.
I agree its level is highish, particularly because of the Rego requisite, but far from unreachable even for a starting character.