Crane flies belong to the Tipuloidea, a group of true flies unrelated to mosquitoes except at the level of the order Diptera. Their mouthparts are not adapted for piercing skin. Many adults take only water or nectar, and a large number do not feed at all in the winged stage, living just long enough to mate and lay.
Two separate folk names collide here. In parts of Britain and North America the crane fly is called daddy longlegs, a name also given to cellar spiders and to harvestmen. The claim that any of them is highly venomous but unable to bite through human skin travels between the three animals and is untrue of all of them.
The real economic story is underground. Leatherjacket larvae feed on roots and can thin turf and pasture where they occur in high density, which is why crane flies matter more to greenkeepers than to anyone worried about being bitten.