June bugs (Phyllophaga) are common nocturnal pests whose adult stage emerges in late spring and early summer. These reddish-brown to black beetles feed on the foliage of trees, shrubs, and garden plants. The adults chew through leaves, resulting in a characteristic “skeletonized” appearance or ragged holes that can stress the plant and reduce its ability to photosynthesize. Managing these pests involves immediate action against the adult beetles and long-term strategies to control their destructive larval stage, known as white grubs.
Physical Exclusion and Hand Removal
Protecting valuable plants from June bug damage often starts with a physical barrier. Lightweight, fine-mesh netting or specialized floating row covers can be draped over vulnerable plants and secured to the ground. This prevents adult beetles from landing on the foliage to feed or accessing the soil beneath to lay eggs.
Hand-picking is an effective, non-chemical way to manage smaller infestations, especially since adult June bugs are clumsy and slow-moving. The best time to perform this task is during the early morning or late evening. During these cooler periods, the beetles are less active and easier to spot resting on leaves.
Once removed, collected beetles should be dropped into a container filled with soapy water. Dish soap reduces the surface tension, causing the insects to quickly drown. Consistent manual removal significantly reduces the number of adults that survive to reproduce, impacting the size of the next generation.
Immediate Control Methods for Adult Beetles
When adult June bugs are actively feeding, contact sprays offer a rapid solution to control the population on foliage. Simple insecticidal soap sprays penetrate the insect’s protective outer layer, causing dehydration and death. A homemade version can be created by mixing two to three teaspoons of mild dish soap per gallon of water and spraying it directly onto the beetles.
Botanical sprays, such as Neem oil, provide another effective option, working both as a contact insecticide and a repellent. Neem oil contains azadirachtin, a compound that interferes with the insect’s feeding and life cycle. Apply the spray in the late afternoon or evening, following the product’s dilution instructions carefully. This timing is better for the plant and reduces the risk of harming beneficial pollinators that are less active at night.
Trapping is another strategy, though it must be used with caution, particularly with commercial pheromone-based traps. These devices use a chemical lure to attract beetles, but they may also draw more June bugs to the immediate area than would have arrived naturally. If a trap is used, place it far away from the plants being protected, perhaps near a property line, to intercept the beetles before they reach the garden. Simple light traps, consisting of a light source suspended over a bucket of soapy water, can also be used at night since June bugs are strongly attracted to light.
Long-Term Prevention Through Grub Control
For sustained control, the focus must shift to the soil to target the larval stage, white grubs, which feed on plant roots for one to three years before emerging as adult beetles. Applying biological controls to the soil is an environmentally conscious method for reducing future populations. Beneficial nematodes, specifically species like Heterorhabditis bacteriophora, are microscopic worms that seek out and parasitize the grubs in the soil.
These nematodes are mixed with water and applied to moist soil in late summer or early fall when the grubs are small and feeding near the surface. Another biological option is milky spore disease, caused by the bacterium Paenibacillus popilliae. This is primarily effective against Japanese beetle grubs and less reliable for all Phyllophaga species. Milky spore works slowly, taking a few years to establish in the soil, but it provides long-lasting control once established.
Cultural practices also make the area less appealing for female beetles to lay eggs. Keeping the lawn well-maintained and slightly longer (three to four inches) deters females from burrowing into the soil. Proper lawn watering and regular dethatching removes the thick layer of organic material that provides a prime feeding environment for newly hatched grubs.