NM
What is this grub in my lawn?
I had what I thought were bird holes in the lawn, but I’m starting to think it’s actually these causing it. I assumed the birds were digging for worms, but now I reckon they’re after these instead.
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That is Porina, you need to get some Grub+ on the lawn leave it on the leaf for 24 hours as they come out at night and feed. If you put a big drop of dishwashing liquid in a bucket and pour it over the holes you'll see them come to the surface after a few minutes.
This is porina, a New Zealand native caterpillar that feeds on turf from late summer through into winter. The small holes are burrow entrances. By this point in the season the caterpillars spend the day in vertical burrows in the soil and come up at night to feed on the grass blades around the burrow opening.
You'll often see dead patches around the entrance to those burrows where they've eaten the grass. Damage usually becomes visible from late autumn into winter as the caterpillars get bigger and eat more. If you want to see them, head out at night with a torch and check around the holes. They’ll be up feeding on the leaf.
NZLA Grub+ is the product to use at 15mL per 100m² in a minimum of 4L of water. With porina, leave it on the surface for 24 hours before watering it in the next day. They feed on the leaf at night, so you want the product sitting on the grass initially.
Grub+ isn't an instant kill like contact insecticides, but the difference is the residue activity lasts 6 months where these contact insecticides are gone within a week. You may still see them alive a few days after application, but they stop feeding before they die so don't worry about that. They normally die in their burrows, whereas with contact insecticides they die on the surface.
Grub+: https://www.newzealandlawnaddicts.com/products/nzla-grub-lawn-insecticide/
I made this video a while ago that you might find helpful: https://www.youtube.com/watch?v=DO0Gk590C18