Crane flies or daddy long legs are among the animals, which cause the most panic in a bedroom, apart from probably spiders, that is. Attracted by the light, they fly in the window and start to flap against lampshades. Apart from this they do no harm at all. Craneflies are merely large flies. They do not feed as adults, nor do they bite or sting. The damage these insects do is when they are in the ground. The female lays her eggs in September, usually in the lawn. The resulting, larvae, called leatherjackets, feed on the roots of plants. They continue to feed throughout the winter and the spring. Identifying the pest is easy. They are dark grey in colour, about 1inch long (2.5cm) and look as though they have no head. In lawns that are effected you will notice that grass growth slows and yellow patches appear, the grass is easily pulled up, with little or no root growth and starlings peck at the grass in an attempt to eat the grubs
You can dig the grubs out of the ground and leave them out on the patio for the birds (I have tried feeding them to the gecko but she won’t touch them), but this proves to be far too messy and time consuming. Another method I find very useful is to put a large sheet of black plastic on the affected area and leave overnight. In the morning when the sheet is lifted there will be the offending leatherjackets ripe for the bird table. There are natural products on the market to kill the leatherjackets. They contain a parasitic nematode called steinernema feltiae, which kills leatherjackets but is harmless to children, wildlife and pets. They are effective when the soil is above 10°c / 50°f, so do it soon if that is the route you want to go down.
There is a chemical you could use from the Co-op too, ask the staff at the counter for details