Grass Grub

Grass Grub (Costelytra zealandica) also known as Brown Beetle is a native species that like many biting and chewing insects has a distinct annual life cycle.

Problem Overview

Grass Grub (Costelytra zealandica) also known as Brown Beetle is a native species that like many biting and chewing insects has a distinct annual life cycle. The adults emerge from October through until February and lay eggs in the soil. They also feed on foliage and may occasionally strip the leaves of cherry and plum trees. The larvae hatch from the eggs after 2 weeks and then inhabit the root zone (20mm – 30mm deep) from March until June eating the roots of susceptible species.

After this time they descend to a depth of 150mm –  300mm where they overwinter.  The damage they cause to plant roots reduces the plants ability to uptake water and the outcome is patches of dead grass particularly through times of drought or sustained moisture stress. The grubs vary in size from 10mm –  15mm in length and are creamy white colouration with a black abdomen. Flocks of birds particularly starlings feeding in turf often indicate a heavy infestation of grass grub.

Solutions

Survey the lawn by taking spade width squares in a variety of areas preferably before damage is noticeable. This is best to occur during the period December to March. Tip the sod upside down and inspect the soil. If two or more grubs are found then apply insecticide at label rates.  

Apply Acelepryn granules from September  - November at a rate of 1.5kgs per 100m2 of lawn. In our experience this product will provide protection for up to 6 months.

OR;

Apply Lawnpro Protect at 330gms per 100m2.

These are insecticides and therefore precautions should be taken to avoid contact and to avoid inhaling any dust whilst applying these treatments. Please ensure that at least 25mm of water is applied within 7 days of application.

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Grass Grub

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Grass Grub (Costelytra zealandica) also known as Brown Beetle is a native species that like many biting and chewing insects has a distinct annual life cycle.

Find a Solution

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