Grubs

Larvae stage of European Chafer, June Beetles and Japanese Beetles.

Identification

grubs2White grubs are the larvae stage of Japanese beetles, June Beetles and European chafers. The grubs are whitish to yellowish and have fleshy c-shaped bodies. They have tan or brown heads and 6 legs. The adults do eat some plants but it is the grubs that do the most damage in a lawn. Grubs can be found in the soil in most gardens and turf areas. A few grubs are normal; it is only when they reach damaging levels that a control should be used.

Evidence

Grubs feed on the roots of many plants, but prefer the fibrous roots of turf. The turf will pull up easily and wilt and turn brown. Often small mammals and birds will pull back the turf
in search of grubs.

grubs

To determine if you have a grub problem,
cut out a one foot square section of turf near the damaged areas and pull back the grass.

If there are 10-15 grubs you may have a problem.

Control

You can greatly limit adults from egg-laying in your turf by keeping your grass cut high and on the dry side. Other control measures include:

Plant a tree

  • Beetles avoid laying eggs under tree canopies, the presence of trees will reduce egg laying in those areas and result in lower grub numbers. 
  • Trees will shade the grass area helping it to survive drought conditions and thus helping it to survive some feeding damage. 
  • Trees will attract birds, which feed on grubs and beetles to help control them.

Do not irrigate

  • Turf areas that have perennial grub damage or highly irrigated turf areas with few trees during dry summers will almost always have high grub numbers. 
  • Grub eggs may die under very high summer soil temperatures or with very dry soils resulting in fewer grubs and damage the next year. 
  • Reduced irrigation in late June into July when the adults are flying will make a turf area less attractive for adults to lay their eggs on.

Let nature do its job

  • Encourage birds to your yard to feed on grubs, use birdhouses, shrubs and trees. 
  • Grubs will feed in the spring and the damage will show up in the heat of August, but if it is a dry summer (on non-irrigated turf), the eggs that beetles lay will not easily hatch. So the damage will be done, but next year there will not be as many grubs.

Keep your lawn healthy

Mow high

  • Beetles prefer to lay eggs in short grass, so raise your mowing height in the summer. 
  • Mowing high helps to keep grass healthier by encouraging root growth 

Fertilizers

  • Leave lawn clippings after mowing, because their slow release of nitrogen favours the decomposition of thatch by microorganisms. 
  • Use fertilizers with high potassium and adequate nitrogen to encourage root growth and resistance to stress.