I’ve been getting questions about the numerous June beetles attracted to lights this spring. Callers are wondering if the June beetles are coming earlier this year.
These are the “early-bird” scarab beetles. We could call them “April” or “May”beetles, though the term would be a loose one. There are several species of scarab beetles, relatives of our June beetles, that typically emerge earlier in the season.
It turns out that Texas boasts dozens of species of scarab beetles that share some resemblance to our common June beetle or June bug. One of the differences among species is the preferred food. Some of these beetles feed on composting vegetable matter, others on tree or shrub or flower roots, still others on turf grass, corn or other grassy plants. Fortunately, only a few species are damaging or regularly abundant enough to damage lawns and gardens.
Scarab beetles can be identified by their heavy bodies and long, spindly legs. This body design is better for digging than crawling in most species. Try to contain a beetle in your hand, and through the scratching and tickling, you’ll see how powerful these digging insects can be.
All of these pests appear roughly around late April through June, have roughly the same body shape with the oval back and pincers at the front and feed on the leaves of landscape plants.
The June beetle and southern masked chafer emerge from the soil and fly at night, usually after a significant rainfall or irrigation. Flight periods may last for several weeks, during which time mating and egg-laying occur. During flights, large numbers of adult beetles, primarily males, may be attracted to lighted windows or other lights at night.
Females, being less active fliers, usually are less common around lighted areas than are males. After mating, female beetles dig 2 to 5 inches into the soil to lay eggs. Each female can lay up to 30 to 40 eggs, which hatch in approximately two weeks.
For this reason, turning off outdoor lights during adult flight periods may not substantially reduce subsequent damage from the well-known white grub. And it’s why heavy white grub infestations that eat up your lawn’s roots often can be found in areas with little or no outdoor lighting. Most damage from white grubs occurs during mid-summer to early-fall when the larger larvae are actively feeding.
Knowing their life cycle can help us determine when control is best accomplished. Once a year, in late spring or summer, adult beetles emerge from the soil to mate. Mated females then return to the soil to lay eggs. Within about two weeks the eggs hatch into small white grubs that feed on grass roots. The pupa, or intermediate stage between the larva and the adult, occurs the following spring and is the last immature phase of the insect’s development cycle.
It is when the larva (grub worms) are young that they are most easily controlled. Soil based insecticides applied six weeks after they finish flying is a good time to treat.
Another possible way to possibly mange the grubs is through the use of milky spore which is applied to the lawn and then allowed to populate the lawn with a “disease’ that affects the grubs. It will take a few years to build up populations that are going to be effective.