I used to have some patches of lawn with dry and sandy soil underneath and
it has been very difficult to grow a good lawn there.
It's difficult to keep enough moisture in sandy areas. This makes grass grow more slowly in those areas and white grubs love this kind of soil.
They
eat the grass roots causing the grass to turn brown. An already weak lawn
is then completely destroyed by the grubs.
These white grubs, the larvae of the European Chafer, have a one year life cycle. The adult beetle, resembling a June bug (a big brown beetle that can fly), lays eggs around the end of June which subsequently hatch into baby white grubs. The grubs feed on grass roots from August to November. The grubs burrow deep in the soil when frost arrives. After the spring thaw they come again up to the surface to eat more grass roots. Finally, they change into beetles and emerge from the ground in mid-June. They mate and lay their eggs into the soil of the lawn. The beetle prefers areas of the lawn where it can easily reach the soil. To not cut the lawn too low in June and July offers some protection.
Grubs are an attractive food source for raccoons and skunks. The "help" you by removing them from the lawn but unfortunately they tend to dig-up everything and damage the lawn further. It's a good time to re-seed after those friends have taken out the grubs.
A white grub, the larvae of the European Chafer (June bug).
The European Chafer, June bug
I started to investigate this problem and this was when I stumbled over http://cloverlawn.org/.
Instead of getting mad about the grubs, trying to rake them out or trying to attack them
with expensive nematodes, I just seeded the area again with a mixed of grass and white clover.
It's perfect. The clover is very beneficial for the grass. It protects it against white grubs and provides nitrogen to the grass. Clover has the ability to
bind nitrogen from the air into a form of nitrogen that can be used
by other plants (natural grass fertilizer).
A patch of clover lawn. This used to be an area infected with white grubs and now it's a healthy lawn.
My lawn remains still a bit green during a dry summer when other
lawns are brown. The clover is more drought resistant than grass and stays
therefore longer green.
Clover is not a weed. Don't listen to the fertilizer and herbicide industry. A lawn with a bit a clover in it is so much easier to maintain and the flowers are nice too.
Seeding clover
There are many types of clover. Some types used by farmers as agricultural cover crop grow too high for a lawn.
Look for seeds of clover types that are meant to be used as a lawn such as Micro Clover or White Dutch Clover. Most garden centers with an organic or eco product line will have such clover seeds in stock.
white dutch clover seeds
Add about 3-5% of clover seeds to grass seeds when you sow a new law. It's not
good to add too much clover. 3-5% gives a good lawn with a bit of clover
in it. You can as well just add clover seeds to your existing lawn. Clover
needs some space to grow. Cut the grass low and rake it a bit to thin
it out and remove dead grass. You would probably want to add clover in areas where the
grass is not growing well and already thin. In other words the space
that the clover needs to grow is probably already there. Again watch out
to not add too much clover.
The ratio of clover to grass will change over time. This is normal
because some areas are more favorable to grass and others more favorable
to clover. You will get patches with just clover (just as you will get patches with just grass). Those patches with just clover
are usually places where lawn would have become brown and thin over time (areas close
to the street where salt from the winter damages the grass, areas where it
is too dry, areas with too much shade, ...).
Note that clover is drought resistant as an mature plant but sufficient water
availability is critical to the success of the seeding.
With clover in the lawn you will get rid of the brown spots in your lawn
and it will be green everywhere. It's easy to maintain, requires less
frequent mowing and there is no need to use fertilizers to get a strong lawn.
So don't add any fertilizers just leave the clippings on the lawn.