The life cycle of a crane fly, from leatherjacket grub to adult crane fly.
An image showing the life cycle of a leather jacket grub transforming into a crane fly. It spends the majority of it’s life underground, eating roots of plants. This is why it can be a devastating lawn pest.
Find out more about leatherjackets and your lawn in my complete guide to Leatherjackets.
More pages about leatherjackets:
Is April the best time to apply nematodes to get rid of the leather jackets
The best time to apply is two weeks or so after you see the adults. This is usually late summer / autumn.
The grubs are too big for nematodes to have any noticeable affect in spring.
I wouldn’t rely on them though. They are only and organic treatment and will not provide complete control.
Given the life cycle, I guess August/September would be the best time to renovate a lawn to disturb the multiplication and life cycle?
You want to do the renovations after the adults have flown and laid eggs (as they prefer disturbed lawns), so October is generally best if Leatherjacket damage is a concern.