Grubs—without a doubt, are one of the biggest fears of homeowners when it comes to their lawn. Known for causing irregular patches of dead grass randomly in your yard, these menaces are the larvae of different scarab beetles like Japanese beetles and June bugs.
If you’ve landed here on this page, the chances are high you have grubs in your lawn and are investigating products to get rid of them. There are two different products available—grub preventers and grub killers—and it’s critical to understand the difference between them because they work differently.
- Grub preventers contain an ingredient that targets the eggs and young larvae, so they work to control grubs in their early life stages.
- Grub killers target active mature grubs in your lawn, killing on contact.
Grub preventers offer the best protection, but application timing is critical. These products only work on eggs and young larvae, so applying them right before or when the eggs hatch is necessary. If applied too early, the active compounds may break down or move down through the soil before larvae hatch, making them ineffective.
Apply grub preventers containing imidacloprid, thiamethoxam, or clothianidin in late spring or early summer. In most areas, this is June or July. Chlorantraniliprole-based products take longer to move into the soil, so they need to be applied in April or May.
Grub killers can be applied at any time of the year you see grub activity. They contain carbaryl and trichlorfon, killing grubs in all of their life stages. They aren’t as effective at reducing grub populations as preventers; they work the best when applied in the fall.
Life Cycle of Grubs
Due to their differences, the products must be applied at precise times of the grubs’ life cycle to work effectively. Regardless of the type of grub you’re dealing with in your yard, they go through four distinct life cycle phases: egg, larvae, pupa, and adult.
- Eggs are typically laid June through August.
- After hatching, larvae feed on the turf’s roots close to the surface, continuing until late fall. This is when you may start to see damage to your lawn. At this time, they are the most vulnerable to chemical control.
- As temperatures drop, the larvae move down through the soil to be below the frost line, where they can overwinter safely. They cannot be controlled at this time because they are too far beneath the soil surface.
- In early spring, the larvae move back to the surface and feed voraciously in preparation for pupation. This is when the damage is most evident, but the larger larvae are less vulnerable to chemical control because their outer skins are thickening. After feeding for a while, the larvae begin pupating.
- Adult beetles emerge from the soil through the surface. The adults then mate and lay eggs.