Gardeners that have problems in the lawn with either of these two pests should take note that both are coming up towards maturity at this time and will do the maximum amount of damage.
With porina caterpillars, they live in the soil and come out after dusk to feed at the base of your grasses.
They are fairly easy to control with a spray of Neem Tree Oil. This should be applied late in the day to the lawn after it has been recently mowed. Repeat again about 4 weeks later.
Grass grubs on the other hand are much more difficult to control and dependant on the size of your lawn a more expensive job. Likely there is little need to treat the whole lawn with a control as the biggest number of the grubs will be where there has been problems in the past. This is also true in areas where they are lite after dark, by street lights or security lighting. In my book, Wally’s Down to Earth Gardening Guide I give an excellent way to control the pest in early summer when the adults are on the wing.
Before you start to spend your money to treat the lawn you should check to see how many grubs are in the lawn. This is done by cutting several small squares with the spade and lifting the turf. Examine both the hole and lifted section for the number of grubs. If there are none or only a few then it is not worth worrying about. (Use the summer control of the beetles) But if a good number is found then that area should be treated.
There are two treatments that you can use and the first of these is Neem Tree Granules sprinkled on the lawn and lightly watered in. The granules break down and release the Neem properties which are taken up by the roots. When a treated root is chewed on by a grub, that will be the last bite it ever takes.
Safe for pets and wildlife including birds as Neem only harms insect pests.
For those gardeners that like to use a strong chemical then use Pyrifos G. It too is a granule that is spread at the rate of 2 grams per square metre. (Needs to be applied with a spreader).
It is a strong poison and you need to take great care in handling and prevent pets and children from using the target area till it is well absorbed into the soil.
Diazinon is another chemical treatment but does not work well in all soil types (best used only in light, sandy or volcanic soils) otherwise it can be a costly exercise for no advantage.
The utmost care must be taken if using either of these two chemical products.