Grubs: Friend or Foe?
It is a common misconception for homeowners to think that when they see a grub then there is a problem. Here in North Texas lives approximately 12 species of grubs and only 2 of those grubs actually feed on the roots of turf grass. Even then, they can only cause damage in very large numbers.
A lot of the time we receive calls from concerned customers in mid-late spring about the discovery of grubs in their flower beds and yard while they’re digging around. This is completely common and nothing to be afraid of. It is especially common to find grubs in your flower bed because they love a nutrient rich soil to feed in. They munch on organic material and can play an important role in the soil food web.
THE LIFE CYCLE
It is important to understand the life cycle of a grub first to then understand when the right time to treat is. In the late spring/early summer adult beetles emerge from the soil to mate. After mating, the adult females return to the soil to lay their eggs. From the time of the first flight of the adult beetle, it takes about 5-6 weeks for the larva to be in the root feeding stage of their life cycle. In North Texas this is anytime from late July through August.
SIGNS OF DAMAGE AND CONTROL METHODS
Grubs don’t discriminate on the turf varieties they like to feed on. If your turf is turning brown, a tale tell sign that grubs are at play is if it lifts up and can be rolled over like carpet. Most of the time when you pull up the turf, you’ll see grubs present. Anywhere from 6-10+ grubs per 1 sq ft is considered an infestation.
If damage has already begun, it is best to act fast and effectively. The organic option is beneficial nematodes. It is important for there to be adequate soil moisture when applying nematodes so they can burrow down in the soil to attack the grubs.
The non-organic option is treatment with a systemic chemical. Since they feed on the roots, systemics work the best because it ensures uptake of the insecticide. Sometimes this is a more effective route at controlling the grubs if significant damage has already occurred.
Since our company focuses on organic approaches to lawn care, we find it counter productive to apply preventative grub control to all of our clients’ yards. While this pest can be devastating to your grass, it is not very common that it will happen to your lawn. Often times insecticides do not discriminate between good and bad bugs. Therefore, over application of insecticides can cause an imbalance in your soil’s ecosystem. We find that the best approach to disease management is from a reactionary standpoint.
image courtesy of https://www.usga.org