Nemasys Leatherjacket Killer (Spring / Summer 50sq.m)


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£19.99 (VAT incl.)
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What are Leatherjackets?

Leatherjackets are the larval stage of the crane fly or daddy-long-legs, they are are about 2.5cm (1" long), greyish black in colour, legless and with no distinct head (see pictures above).

Also known as Tipula paludosa (European crane fly) or Tipula oleracea (Marsh Crane Fly).


How can I control Letherjacket larvae?

Use Nemasys Leatherjacket Killer to deal with a leatherjacket infestation, without any of the precautions associated with harmful chemicals.

Nemasys Leatherjacket Killer is incredibly effective and is 100% safe for children, cats, dogs, other pets and wildlife. 


When can I apply Leatherjacket Killer Nematodes?

  • Autumn application - typically late August through to the end of October:

When you start to see the adult daddy-long-legs in your garden (towards the end of August) you will know that in a few days they will be laying eggs. These will hatch quickly; therefore aim to apply two weeks after you see the adults.

This is when the young leatherjackets are active in the soil and is when they are most susceptible to the nematodes.

  • Spring application - typically April to June / Summer application July to August:

If you have discovered Leatherjackets (not daddy long legs) at any other time of year i.e. in the spring/summer then treat at double strength as the mature LeatherJackets are much harder to kill -  you must treat in autumn as well.


Where a severe LeatherJacket infestation is present, multiple treatments over an extended period (spring and autumn) may be required.

Leatherjacket Life Cycle and nematode application

Tipula paludosa (European crane fly) Leatherjackets have one generation per year. The adults emerge from pupation from July to September and almost immediately lay their eggs (peak emergence can vary regionally). The larvae hatch out after about 14 days and start to feed on the bases of stems and roots immediately (this is when they are most vulnerable to nematodes), they become more active and feed voraciously in the spring when the soil begins to warm (the second opportunity to treat with nematodes but at double strength).  When fully grown they reach approximately 3-4 cm in length and then stay within their burrows for about 6-8 weeks before making their way to the soil surface to pupate and the cycle repeats. 


How do Leatherjacket Killer Nematodes work?

The nematodes (Steinernema feltiae), seek out the leatherjackets and attack the pest by entering natural body openings. Once inside, they release bacteria that stops the pest from feeding, quickly killing the pest.

The nematodes then reproduce inside the dead pest and release a new generation of hungry infective nematodes, which disperse and search for further prey.

Beneficial nematodes are living organisms, so they must be used before the expiry date (which is marked on the inside of the pack and will be around 2-3 weeks) and should be stored in the fridge until it is applied.


How do I apply LeatherJacket nematodes?

Prior to applying the nematodes:

  • Cut the grass short before treatment.
  • Soil should be between 10°C and 30°C during application and for at least two weeks after.
  • Irrigate the area to be treated prior to application in order to apply the nematodes to a moist lawn.

To avoid desiccation of the nematodes:

  • Avoid direct sunlight; make applications in the evenings or in dull conditions
  • Application during rain is highly desirable.
  • It is very important to irrigate immediately after application, water the grass well so the nematodes are washed below the thatch layer into the soil to reach the roots where the larvae will be feeding.
  • Ensure soil is moist for at least two weeks after application.

Leatherjacket Killer application instructions using a Hose-end Feeder (50 sqm Pack):

Before starting, mark out the area to be treated - this will help ensure even coverage.

  1. Add half of the contents of the pack to the bowl of the feeder. 
  2. Fill the bowl with water, mix thoroughly until fully dispersed and attach the hose.
  3. Set the Miracle-Gro® Feeder spray pattern to ‘flat’ and watering mode to ‘feed & water’.
  4. With the feeder in an upright position, apply evenly to half of the area using a side-to-side motion. Application will take approximately 8 minutes under typical water pressure conditions.
  5. Repeat the above procedure with the other half of the contents of the pack to treat the other half of the area. 
  6. To make sure the nematodes are adequately watered in, treat the same area again for a further 8 minutes if treating a vegetable patch or 16 
    minutes if treating a lawn. Applications to lawns require more water to wash the nematodes through the grass thatch.

Adhering strictly to the application timings will ensure that any remaining colour in the bowl will be due to the inert carrier only and that you have performed an even application.

IMPORTANT: Make sure the lawn does not dry out after applying nematodes and keep it well watered for at least two weeks.

Watering can application (using 0.5 litre stock solution):

How to use:
1. Dissolve the entire contents of the pack in a bucket containing 5 litres of water to create a stock solution.
2. Stir vigorously and immediately take 0.5 litre of the stock solution, add to a watering can fitted with a very coarse rose and fill with 5 litres of water.
3. Apply the solution to a tenth of the soil area to be treated.
4. Repeat steps 2 and 3 until the whole area is treated.
5. Water the treated area thoroughly after application.

This method fills 10 watering cans of 5 litres and treats up to 50m2

IMPORTANT: Make sure the lawn does not dry out after applying nematodes and keep it well watered for at least two weeks. 


Which pack size do I need?

To calculate your area measure the width and length of the area to be treated and multiply them by each other e.g. 5m x 10m = 50 sq.m


Leatherjacket Killer - Spring application must be made at double strength - therefore this pack treats 50 sq.m - even though the outer sleeve shows 100 sq.m.

Can't see an answer to your question? Please contact us and we will be happy to assist you.

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Our lawn was looking awful to the point we thinking of taking it up and laying new! A friend noticed the massive dead patches and said leatherjackets you need nematodes? We bought a bracket of the leatherjacket killer and wow we have a lawn back and green we are planning another application spring to give the lawn a boost. Definitely recommend this product.