You're relaxing with a drink on your porch when, all the sudden, you're hit by a flying insect. You look down and see that the culprit was a beetle—more specifically, a June bug. These pests can be a nuisance to you out on your deck during the evening in early summer because they will be attracted to any lights you have on, though they can't do much harm to you. Your landscape, however, is not so lucky.
What Are June Bugs and What Damage Do They Cause?
Part of the problem in discussing "June bugs" is that this common name is deceiving on two counts:
- A number of different insects go by this common name, and not all of them are equally destructive to the landscape in all parts of the Northern Hemisphere.
- Even where we are discussing a particular species, different common names are used. While "June bug" is most popular in some regions, in others, "June beetle" or "May beetle" may be used.
All June bug species are considered scarab beetles, all start out as a larval form known as "grubs," and all appear as adults in the garden in late spring to early summer. Both the adults and the grubs can cause landscape damage. Note, though, that not all beetles are bad: Lady beetles (Hippodamia convergens) are quite beneficial.
June bug grubs are most notorious for damaging lawn grass (they live underground and eat grass roots, causing die-back in your lawn), while the adults can eat the leaves of trees, shrubs, vegetable plants, etc. But the extent of the damage caused by the adults can vary not only from region to region but also from year to year. For example, some years in New England (United States), one type of June bug, the Japanese beetle (Popillia japonica), will devastate the squash plants in your garden, while during other years, they may be strangely absent.
Perhaps the insect most strongly associated with the common name of "June bug" is Phyllophaga longispina. Unless otherwise noted, it is with Phyllophaga spp. that we are dealing here (although most of the information applies equally to other types of June bug).
Signs of a Problem (Even if You Don't See Beetles or Grubs)
There are a few indicators that let you know that you may have a problem either with adult June bugs or their larvae:
- You have brown patches in your lawn.
- Small holes are being dug in your lawn overnight. These holes are often made by skunks searching for grubs, which are a food source for them.
- Moles also eat grubs, so, if you have a mole problem, the source of it may be a grub problem.
- Holes are being chewed in the leaves of some of your plants.
Monitor your landscape for such signs and follow up upon their detection by confirming the presence of these insects. For confirmation that grubs are present, simply dig up some sod in your lawn and inspect the soil for grayish-white, caterpillar-like bugs that vary from less than an inch to slightly more than an inch long (they curl up into a "C"-shape when disturbed). For confirmation that the adults are present, walk your landscape faithfully and inspect the leaves of your plants for beetles.
Taking effective, timely action is a great way to prevent problems from June bugs and their grubs.
Best Way to Get Rid of June Bugs
The "best" way, in this case, refers not so much to a method as it does to timing. Do not wait until the adult beetles are present before practicing pest control. It is far better to target the grubs rather than trying to kill the adults. The grubs are contained in a defined space, underneath your grass. This makes it easier to wipe them all out. By contrast, the adults, as flying insects, could be anywhere.
The life cycle of June bugs varies according to species, but here is a typical scenario:
- The females deposit eggs in the lawn in mid-summer.
- The grubs soon hatch out and remain near the soil surface till fall.
- They burrow deeper into the ground for winter.
- They emerge from the ground in spring as adult beetles.
To kill the grubs, apply an insecticide that contains carbaryl or trichlorfon in September. At this time, they are still close enough to the soil surface to be susceptible to an insecticide.