Leatherjackets
Tipula and Nephrotoma spp.
also called Crane fly larvae, Daddy-long-legs grubs
Tough gray-brown legless grubs eating grass roots and seedling stems below the surface. Birds tearing at the lawn in spring are usually telling you they are there.
How to know it
A leathery, legless, grayish-brown grub 25–40 mm long with no obvious head — the tough skin is what gives it the name. It lies just under the turf or in the top few centimeters of soil. The adults are the familiar crane flies bumbling around lights in late summer.
What you'll see
- Yellow, thinning patches in the lawn in early spring that do not respond to feeding.
- Turf that lifts easily because the roots have been eaten, though less cleanly than with white grubs.
- Crows, starlings, rooks and badgers tearing at the lawn and leaving it torn up.
- Seedlings and young transplants cut off at or just below soil level in a border.
- Grubs turned up whenever the top few centimeters of a lawn edge are dug.
Where it comes from
One generation a year. The crane flies lay in damp turf in late summer — a wet August is what makes a bad year — and the grubs hatch in autumn and feed on roots through the winter and into spring. They do most of their damage in March and April when they are large and the grass is trying to start growing. They pupate in late spring.
Wet autumns and damp, poorly drained lawns. Heavy soils, shaded lawns and areas of long grass at the boundary all carry more. New lawns laid on ground that was rough grass are particularly prone.
Dealing with it
- Water in parasitic nematodes (Steinernema feltiae) in early autumn while the grubs are small and the soil is still warm — the timing is everything, and spring applications work far less well.
- Water the lawn heavily in the evening and cover it with black plastic overnight; the grubs come to the surface and can be swept up in the morning, or left for the birds.
- Improve drainage on a lawn that is repeatedly affected.
- Feed and water the damaged turf in spring so it can outgrow the loss.
- Reseed the bare patches in autumn.
Keeping it out
- Improve drainage and aeration, which is what makes a lawn attractive for laying in the first place.
- Keep the grass slightly on the dry side in late summer during the crane fly flight.
- Apply nematodes annually in early autumn where it is a recurring problem.
- Cut long grass at the lawn edges before the flight.
- Encourage starlings and other probing birds, which are the natural control even if the digging is untidy.
What it goes for
Lawn grasses above all; also seedlings of brassicas, lettuce and strawberries in beds next to grass.
Who hunts it for you
- Beneficial nematodesSteinernema & Heterorhabditis spp. Microscopic worms watered onto damp soil that hunt down soil-dwelling grubs and release a bacterium that kills them within days. Timing is the whole thing: warm, damp soil and a small target grub, which means late summer for most of what they are used against.
- Garden birdsPasseriformes Both things are true: birds strip your currants and a brood of blue tits takes several thousand caterpillars out of one fruit tree in a fortnight. Net what you must and welcome them everywhere else — a nest box near the apples is worth more than a spray. Grow to recruit it: Echinacea,Elderberry,English holly,Goldenrod,Rudbeckia,Sunflower
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com