Leatherjackets, the Larvae of Crane Flies, can Destroy the Lawn that you have Worked so Hard for; but there are Methods to Identify and Control these Pests
Identify the Cause of Brown Patches in Your Lawn
leatherjackets Leatherjacket larvae, if they are left un-treated, can cause severe damage to lawns and will then over winter deeper in the soil, ready to cause more damage the following spring. They cause lawns to develop yellow patches where the roots have been eaten by the grubs of the Leatherjacket. In severe cases the roots are completely destroyed and the turf can be pulled up easily to reveal no roots! Secondary damage from birds and animals is just as destructive, as they often dig up lawns looking for the grubs to eat.
Nematodes are the Green, Organic Solution to Leatherjacket attack.
Leatherjackets are the larvae of Crane flies; more commonly known as Daddy Long Legs. These larvae hatch from Crane Fly eggs and appear as grey or brown grubs living in the soil just beneath the grass and feasting on the roots and stems of your lawn from early spring and throughout the summer until early October.
The eggs are laid in the soil by the young adult Crane Flies in the early autumn. The peak egg-laying period is around the second week of September, depending on the weather. The eggs hatch after two to three weeks and the larvae start feeding and continue throughout the winter.
leatherjacket spots on lawn If you don’t treat the leatherjacket grubs, then you will also see a large number of Crane flies hovering about the lawn area as the grubs metamorphose and emerge as Daddy Longlegs Flies.
These adults lay eggs in the lawn during autumn, which soon hatch and start feeding on the roots of the lawn. Feeding normally stops in winter – unless the weather is mild – but soon resumes again in the spring – thereby completing the cycle of attack.
The sign that your lawn is infested with these grubs are patches of dead or dying grass. There may be a number of causes of dead and dying patches in a lawn however, and it is important to investigate to determine what has caused the problem in your lawn before going on to treat it.
Signs of pest activity are often found in stressed areas such as the edges of lawns or in shady or wet areas (I have these areas in abundance!); look for spots with discoloured, stunted or distorted turf and, as the larvae tend to start eating at the central point and work outwards, the edges of the patch are where you will find the culprits.
Leatherjacket larvae, left un-treated, can cause severe damage to lawns and over winter deeper in the soil, ready to cause more damage the following spring. In severe cases the roots are completely destroyed and the turf can be pulled up easily to reveal no roots! Secondary damage from birds and animals is just as destructive, as they often dig up lawns looking for the grubs to eat.
There is little point repairing the damage until you have killed the larvae.
Fortunately there is an alternative to digging up the whole lawn and starting again! Insecticide can be used in October until late spring or early summer, depending on the moisture content of the soil and the temperature.
Thompson & Morgan also sell a Natural Pest Control Leatherjacket Killer in the form of specific nematodes which infect the leatherjacket larvae and kill them. The nematodes should be applied after the Daddy Long legs or Crane flies have laid their eggs in the grass and these eggs have developed into the Leatherjacket Larvae.
Nematode Leatherjacket Killer is harmless to children and pets, which is a distinct advantage, but the product must only be used between August and October.
Prevention, as always, is better than cure so you may need to repeat the treatment every year. It is said that Leatherjacket adults always return to their place of birth to lay their eggs, so if you don’t treat them at the first sign of attack, the lawn will suffer year after year from the invasion by the adults.
Do not underestimate the damage that can be done – just watch the groundsman’s face turn white if you report Leatherjacket attack at your local golf course!