Grubs attack from below in the months of June – November, these unseen but quite damaging menaces attack our lawns from below. They are white grubs.
Grubs are larval (immature) stage of several species of beetles including May or June beetles, and masked chafers. The adult beetles feed on the foliage of trees and other plants. The grubs are fat and commonly lie in a C-shaped position. They are dirty white in color with brown heads and with dark areas visible at the rear of the abdomen.
Adult billbugs are snout beetles. The beetles are black and about 3/8 inch
long when mature. Billbugs are found most often on Floritam, but also may attack Bahi and other grasses. The larval stage does the most damage, but both adults and larvae can be found in the soil.
To inspect for grubs and billbugs, cut three sides of a one foot square piece of sod about two inches deep with a spade at the edge of one of the off-color areas in the lawn. Force the spade under the sod and lay it back. See if the grass roots are chewed off and sift through the soil to determine if larvae are present. Replace the strip of sod. Inspect several areas in the lawn. As a rule of thumb, if an average of two or three grubs or five billbugs are found per square foot, apply insecticide.
Grubs damage the grass by feeding on the roots about an inch below the soil surface. Their feeding causes the grass to turn yellow and then brown. The damage may first appear as spots only a few inches in diameter, but these spots will gradually become larger as feeding continues. Heavy infestations completely destroy the roots, and the grass can be rolled back like a carpet.
When treating for white grubs or billbugs, using a liquid or granular form of insecticide, the turf should be moist at the time of application. Immediately after applying the insecticide, irrigate with about ½ inch of water to leach the insecticide into the soil where the insects are feeding.
The most common insecticide used for grubs, that can be found at your local garden supply or nursery, are Meritt 0.5l or Sevin they come in liquid or granular form. These insecticides work well when there is a minor infestation, but when the problem is more severe. One of the best chemicals on the market is Dylox, Which can only be purchased by professional applicators. And like with most insect problems, with the proper watering, mowing and fertilization, the less stress on your lawn the less problems there will be.