Pests
Eggs are laid in moist soil from February to May, and nymphs (immature adults) emerge from November to January. Adults appear from February and live for two or three months inhabiting cracks in the soil and emerging to feed on the leaves of the grasses. They take the closest plants first and as a result a bare patch around their home is very evident. They are visible throughout the day and move quickly when disturbed by foot traffic.
The adult black beetle is approximately 15mm long and has a black and sturdy appearance. As an adult it can be found throughout the year but most predominantly from the months of February though until October.
The adults burrow into the soil where they also consume the roots of grasses. The larvae are creamy white in colour with a black head and abdomen. They live in the top 10mm-50mm of the soil profile with most of the damage done from October through to March. You know if you have an infestation if your grass is dying in patches for no apparent reason and the lawns has a damaged root system, and the grass looks brown and discoloured. High bird activity is also a sign of insect infestation.
Grass grub adults emerge in October and are active until mid-December. The cooler the temperature, the later they emerge. The adults will start to emerge once the soil temperature reaches over 10 degrees.
The grubs that you see in the lawn are the larvae of beetles. These grubs are C shaped, off white in colour with a dark head. They eat the roots of the grass, causing irregularly shaped patches of wilted, dead or dying grass in April and May and again in August to mid-October. Lawns that are heavily damaged by grubs will have a yellowish tinge and will feel spongy when walked on.
Worms are important for the soil ecology, but an over-active worm population through winter can cause lawns to become very bumpy once the castings dry. When the wet castings are smeared over the grass, it can cause an open lawn. We apply worm pellets which are an organic tea extract to control the worms and are very safe to use.
The Porina caterpillar causes similar damage to lawn grass and pastures as grass grub, causing bare patches and an increased incidence of flat weeds. However, it tends to feed on leaves rather than the roots. The caterpillars are greyish yellow with a dark brown head and grow up to 6cm in length.
The adult Porina moth is a fat brown moth that flies around your lights at night. It lays 100+ eggs on grass in spring and summer. On hatching the caterpillars move to leaf bases where they feed. As they grow, they burrow into the soil and emerge at night to feed on the leaves. They do most damage in Autumn and early winter.