Recently we have received a number of reports of Leatherjacket activity in lawns across the country which is quite unusual for this time of year. Usually at this time of year the larvae have travelled deeper underground to overwinter and are dormant, causing no damage. It seems however that the recent mild weather and heavy rainfall has risen the water table in many places, essentially forcing the Leatherjackets out at the risk of drowning.
For this reason, they have become active and begun feeding on grass roots and causing damage.
Usually when these pests are active in the spring and summer, the course of action we recommend is nematode treatment, tiny, microscopic eel worm-like creatures that damage the larval stage of the pest. At this time of year, however, when temperatures are much lower, the nematodes will not be active. Nematodes need a consistent minimum ground temperature of 10 oC, which is most likely not achievable at this time of year.
We recommend beginning nematode application when soil temps rise later in the year around April time, although late summer application will also be needed (August- September) when most eggs are laid and begin hatching.
We anticipate the Leatherjackets will return to their overwintering position once the ground has had time to drain and temperatures drop.