Controlling June Beetles in Your Lawn
June beetles will eat the roots of any small seedling they come across as well (they are not fussy-eaters).
And once the roots are gone, the grass plants will wilt and die.
Grubs In One Spot
This normally happens in patches because all the grubs hatch from one egg-laying spot and they are not very mobile in the soil.
Adults Eat Trees
Adult beetles also eat the leaves of many trees. This is not normally a problem as there are not usually enough adults to really hurt an established tree.
June Beetles take three years from egg to adult. The females lay eggs in June in grassy areas – usually next to houses as they are attracted by the lights at night. The eggs hatch in a few weeks and the young larvae feed for the remainder of the summer. They retreat deeper into the soil to overwinter.
The second season is when the serious lawn damage is done by the sophomore grub. It eats constantly from early spring right through until late fall when it once again heads for deeper ground to overwinter.
The third year, the grub rises to the rootzone, replenishes its energy by snacking on some tasty grass roots and then forms a hard shell to pupate. The adult hatches from the pupa in late summer but remains underground for the rest of the year and over the winter. The following May or early June, it emerges to start the cycle once again.
Adults are black or brown and approximately an inch long. They have long spiny legs that attach themselves to anything they land on, especially kids clothes. There are some 7 species distributed around Eastern North America so there is some variation in color and size.
Larva or the grubs are quite small when first hatched but quickly grow to 1 to 1 ½ inches. They are c-shaped with a large brown head capsule as well as the typical three pairs of legs.
Controlling June Beetles
It is much easier to control small grubs than adults. So the rule of thumb is to apply any controls approximately 3 – 5 weeks after the adults are seen flying.
Did you see large numbers of beetles flying and bouncing off house screens and outdoor lighting? If so, Wait 5 weeks.
Peel back square foot samples around your yard.
Check for white grubs – if there are more than 5 per square foot – treat.
If 5 or less white grubs per square foot, do not treat.
Types Of Control
Predator nematodes work quite nicely to eat this pest.
Here's more information on controlling white grubs
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