Leatherjacket Grubs - Autumn 2020 to Spring 2021
What are Leatherjackets?
- Leatherjackets are the larvae of the Crane fly (Daddy long legs)
- The main variety usually start their Lifecycle in the Autumn but one sub species can appear in early summer but having said that the timing is becoming less predictable as the climate changes
- What we do know is a wet autumn such as we had in 2020 means more grubs are likely to have survived to feed on the grass plants roots and the mild winter on the south coast means the grubs are nearer the surface so damage is showing earlier than usually expected.
- The adult Crane Fly has long legs with a body about 25mm long.
- Commonly active in the late summer to autumn period with each female laying 200-300 eggs. There can be a smaller amount of activity around May.
- The eggs hatch into larvae, called leatherjackets within about 14 days and remain in the soil for about 9 months before pupating into next season's Crane Fly.
- The Leatherjacket exists in the soil from the autumn to the following spring in your lawn, by eating the stems of your grass plants. This results in the lawn beginning to turn yellow and die back in areas.
- Damage generally becomes noticeable during the spring caused by the feeding that occurred the previous autumn and winter.
- During mild winters feeding can continue through the winter and into the following spring. Larvae stop feeding in May / June after which they will pupate close to the surface of the soil. Leatherjackets have one generation a year.
- Secondary damage from birds, badgers, foxes, moles and other small mammals searching and pecking for larvae may become evident.
- Keep a look out for Crane Fly activity throughout the late summer.
- Monitor your lawn in the autumn, winter and spring for larvae activity and secondary damage.
- If you need advice call us.
- There are no longer any pesticides licensed for use to control this pest in domestic lawns
- The two treatments available are:
- This is a biological treatment for controlling leatherjackets in lawns, flower beds and vegetable plots. This is a pathogenic nematode, which is watered into the turf or soil. The nematodes enter the body of leatherjackets and infect them with a bacterial disease. To be effective, the nematode requires soil that is well drained but moist and with a minimum temperature of 12°C (54°F). The turf around the edge of affected areas should be targeted to deal with larvae spreading out from infestation “hot spots” in the lawn. However, by the time areas of infestation become apparent, the soil may be too cold for nematodes to be effective.
- You can apply Nematodes in Spring at double rate, but the grubs are mature and much harder to control.
- As a preventive measure, you can apply nematodes in September to early October, two weeks after you see crane fly in flight. It’s important that Nematodes are applied as soon as possible after purchase; make sure you follow the suppliers’ instructions for use. You need to water the lawn before and for several weeks after application to ensure the soil is sufficiently moist for nematode activity and for them to survive, thinning any thatch layer or aerating before application can help the product reach the rootzone.
- Application of Nematodes does not need a licence and they are readily available on the internet from various suppliers.
- Over the last few months a new product has entered the market, Turfsolv we have not yet used it but have received positive reports.
- The good news is, like Nematodes, it does not need a licence to apply or purchase, so is available directly to the homeowner, it is not a live product so the restrictions on storage and use are not so restrictive
- The even better news is that, although, it needs at least two applications a few days apart, use is not restricted by temperature and whilst it does need watering into the root zone continued irrigation after application is not required.
- That means as soon as grub activity is seen, even when soils are too cold for nematodes this product can be used.
- As always following the manufacturers instructions is key to success, “Apply at 2ml TurfSolv in 100ml water per m2 of grass surface (20 L/Ha in 1000L water). Apply once and then repeat 3-5 days later. Severe infestations of turf pests may require repeated treatments before full recovery of the grass surface is achieved”.
- The application rate and price of the product also means it should be a more economical alternative to Nematodes
- There is a manual way which you can use to try to catch and remove the pests, this involves covering the lawn area, after watering it, with a black plastic sheet or damp hessian sacks at night in damp conditions. Peel back the sheet slowly in the morning and collect up the surfaced leatherjackets. Make sure that you peel back the sheet slowly, for if you just peel it right back, some of the leatherjackets will escape back down into the lawn to get away from the daylight.
- There is a suggestion that garlic extract may keep leatherjacket numbers down and some products have started to appear but to our knowledge are unproven as yet.