Large dead spots that appear in the lawn are caused by white grubs. White grubs need to be controlled properly in order to preserve the lawn. Control applied at the wrong time or in the wrong ways is ineffective and a waste of money. The control has to be applied so it gets to the grubs. This article will look at the cycles of white grubs and how to properly time the control.
White grubs are the larvae of Japanese beetles, oriental beetle, Asiatic beetle, and several other common types of beetle. The grubs range in size but all do the same damage; they feed on the roots of the grass plant and even feed on the stems. Infected grass pulls up like a rug as it has no roots left. Most of the beetles have a one year cycle. This means that they lay one set of eggs per year and a single generation lives each year. Because of this, it is easy to predict beetle activity and treat it to eradicate them.
The beetles hatch in summer and deposit eggs in the lawn during midsummer. The eggs begin hatching in August and September; the eggs and grubs thrive best in well irrigated moist lawns. The larvae eat the feeding roots of the grass, but as they mature begin eating every root. They feed until late fall, hibernate for the winter, then resume their activity in spring. By June, the larvae have finished their feeding and transition into the pupae stage, emerging shortly after as adults, which often ignore the lawn to cause damage in the garden. The beetles lay their eggs and continue the cycle.
Insecticides and beneficial nematodes are the means of control. Follow the label on the insecticide for time of application and instructions on how to apply. Generally, water will need to be applied immediately to get the insecticide to the grubs. Some are preventative while others are immediate. Some only work while grubs are still small. Applying pesticides at the wrong time or improperly inhibits the pesticide’s effectiveness. Apply preventative insecticides if grubs are routinely a problem. Signs of grub activity are yellow spots on the lawn that rapidly turn brown and die, and grass that uproots easily. If conditions are moist, the grass may not turn yellow until severely damaged.
By knowing the signs of a grub invasion, it can be dealt with to deter additional damage. In knowing the habits and timings of white grubs, and through proper application of controls, homeowners can eradicate white grubs from the lawn and minimize damage.