Worms, grubs and various insects have their eye on your lawn but there are simple methods of detection and elimination, so leap into action early for the best result.
These fellows also haunt the underground through most stages of their lives but adults develop wings and disperse to new territory in the breeding season. They are brown, formidable-looking insects, that can grow up to 5cm in length, with stocky front legs made for burrowing. Some species of mole crickets are root-eating herbivores, while others vary their diet to include worms and grubs. Male mole crickets sing lustily from burrows in the grass – their loud song a dead giveaway of their presence. While these insects are often attracted to grass with plenty of thatch – a mat of runners and undecomposed grass clippings on the surface of the soil – they don’t appear too fussy about burrowing into good quality lawn either.
In spring, mole crickets will emerge from their deeper burrows to feed on turf, usually during the night. Females lay their eggs just beneath the soil surface in spring and early summer. Lawn damage is caused both by the burrowing activity of the mole cricket as well as the direct root-feeding that destroys the root system of the plant. Irregular patches of yellowing or dead grass testify to their presence but can be easily confirmed.
Most damage is seen from mid to late summer but by then it is more difficult to control. Do a lawn check early in the season. A simple test for the presence of this insect is a bucket of soapy water – about 4 tablespoons of dishwashing liquid to 2 litres of water. Pour it over an area of about a square metre. Do this early in the morning or late evening in an area where feeding appears to be taking place and crickets will surface within a couple of minutes. If a lemon-based dishwashing liquid is used the soapy liquid will kill them and early action will mean you can deal with the problem without the need for an insecticide.
Lawn caterpillars, or lawn worms appear in the summer months and tend to eat their way right through autumn. These caterpillars thrive in evergreen grass mixes, kikuyu, Berea (LM) and Cynodon lawns. Cynodon is commonly used on golf greens meaning they can also be affected by the voracious appetite of these caterpillars. They are greenish-brown in colour and because they are dormant during the heat of the day and feed at night focusing on the roots of the grass, they are difficult to spot. If untreated, they are literally capable of destroying large areas of your lawn.
So how do you know if the dead patches in your lawn result from lawn caterpillar, or other pests? They are identifiable initially by large, yellow patches in the grass that will eventually die off completely. Place a wet towel over one of the patches and on the following morning check the underside. If you have caterpillars on the towel you have the culprit.
Should you discover lawn caterpillars to be the problem, you will require a recommended insecticide. Again, it is preferable that you spray your entire lawn and not just the affected area, to ensure complete eradication of the pest.
When digging anywhere in your garden you will be likely to discover one or more of these grubs, but is only when there is a severe infestation that they become a problem in your lawn.
These plump, white grubs have a black head with pronounced mandibles, six legs situated in the upper part of the body, and mostly they appear to be curled into a permanent foetal position. White Grub lives beneath the soil feeding on the roots of the grass. In winter they burrow deeper into the earth and hibernate until spring when they return to feed off the roots once more. They then pupate and transform into beetles.
If your lawn feels spongy in places, it may be an early sign of a grub infestation. To check, dig a square of turf about 8cm in depth to just below the roots. Should just one or two white grubs be present there is no cause for concern but five or more in the area of a spade-width is a call to action. More major grass damage will take place in the second year if early signs are not dealt with. When present in large numbers, white grubs cause brown irregular patches to occur in the turf before, eventually, destroying the root system completely. Your grass may lift like a carpet when you investigate the dead patches – a sure sign of white grub problem.
One way to minimise grubs naturally is to encourage birds into your property – a second is to minimise irrigation. A major infestation, however, will need a more radical intervention and you may need to use a recommended insecticide to reduce the grub population