The grubs feed on the excrement for several instars until pupating. This secondary larvae will overwinter in the snail shell before pupating. When the wasp larva hatches, it consumes its still-living host before pupating inside its remains. The larvae develop rapidly within the crane flies before pupating in the soil. When these larvae reach later stages, they turn greenish yellow before pupating. The following spring the third instar larvae develop, pupating in the summer. Before pupating, the caterpillars may wander considerable distances from their host plants. The caterpillars grow fast in warm weather, sometimes pupating within a month. Larvae grow to a length up to 48 mm and take two years before pupating. Before pupating, the caterpillar will turn dark brown. After pupating, the moths emerge from the soil as adults. They resting curled up between the leaves pupating in a yellow boat-shaped cocoon. The caterpillar will turn brown prior to pupating. Before pupating the colouring gets much more diffused. They may wait one or two years before pupating.