The larvae or grubs of June Beetles/ May Beetles cause extensive damage to the roots of lawns and shrubs. June Beetles are sometimes called "May Beetles" in certain parts of the country. The name merely designates which month of the year that the adult beetles are known to emerge from the soil. This page contains information to help you understand the June Beetle and their grubs that destroy grasses of lawns, golf courses and pasture lands. Topics covered include biology of the bug, lawn grub damage and control of white grubs (the name used to cover the larval stages of destructive beetles such as June Beetles, Japanese Beetles, Chafers and others.) An understanding to the life cycle of this insect will be of importance to those responsible for its elimination and control. If grub pest control methods are not timed properly, time and money will be wasted. The timing of insecticide application, type of insecticide to use as well as very important cultural practices will all be covered in the grub control section.
General June Beetle Biology
As mentioned at the beginning of this article, a May Beetle is the same
bug as the June Beetle. The month that the adults are seen as they emerge
from their pupal cells usually designates what locals call the pest in their
part of the United States. (These beetles are called Junebeetle, June
beetles, June Bugs but their proper name is June Beetle)
What we consider a typical June Beetle can vary in color from pale yellow to black but most are brown to dark brown. The Green June Beetle has a different appearance but its damage to lawns in its larval stage is similar to other white grubs and is controlled in the same manner. The adult beetle is known as a night flyer. The Japanese Beetle (another pest whose grubs damage lawns) is a daytime flyer.
Depending on the particular species, area where it breeds and environmental
conditions, the June Beetle can have a cycle that is short as one year or up to
four years. While inspecting lawns for grubs of this pest, people often
report seeing various sizes of grubs beneath their turf grass. This is
caused by over lapping generations of immature beetle grubs that can take 3 to 5
years to complete their cycle.
The white grubs of the June Beetle are C-shaped when they are at
rest. This C shape appearance is common of White Grubs. The newly
hatched grubs are too small to feed on the major root system of plants but they
are capable of eating organic materials in the soil and (as they grow larger)
the smaller hair roots of plants.
June Beetle Damage to Lawns
As roots are damaged by feeding and tunneling, the grass will begin to show signs of stress. Yellowish tinges may appear in otherwise green grass. When infestations are heavy, the turf grass can be rolled away from the ground much as one would roll up a carpet or rug. During seasons of heavy rain or constant irrigation, above ground leaves of grass may not always fade out but these sections will be easily seen the following spring - when the areas do not green up with the rest of the lawn.
Insecticide applications should be applied in mid June to July in most areas. This timing might be different in your area. You want your insecticide to attack grubs in their first instar, while they are young, small and close to the surface. If you observe June Beetles depositing eggs in the soil, you can gauge the timing of insecticide application. As mentioned above, grubs emerge from their eggs about 3 weeks after eggs are deposited into the soil around shrubs and in lawns.
The timing of grub control products is important but is easier than in years past. New, systemic insecticides such as professional strength Merit Granules can help broaden the window of application by several days. This systemic insecticide can give season long control and it can easily stay active in the root system of plants for about 3 months.
For more information, go to White Grub Control and Merit Systemic Insecticides.