The gall is formed when the female lays her eggs and injects a substance into the leaf.

At first the galls are green, and as the larva grows, soften and turn red.

The others members of the group are, This species is found in western, central and northern Europe including France, Great Britain, the Netherlands, Norway and Sweden.

The host larva is killed by the fly and the inquiline feeds on the interior of the gall.

When fully grown the inquiline larva leaves the gall, pupating in the soil.