I am seeing cranefly flying around my lawn since it warmed up in the past week. I understand common cranefly have two generations each year and European cranefly just one. I must have common cranefly since the European emerge in the fall. Is there a benefit to apply Triazicide now or should I wait until fall?
Clackamas County Oregon
It is very rare for common crane-fly to do damage to lawns. Additionally, there is no correlation between many adults flying around and the larvae actually causing damage because there is so much bird predation and death from freezing temperatures. Also, high populations (25 - 50 per square foot) of the larvae are needed to damage a lawn. Finally, since common crane-fly have two generations, if you apply an insecticide in the fall, you are killing both types of crane-fly (common and European).
I rarely apply an insecticide for crane-fly larvae because healthy lawns can tolerate pretty high populations. In general, the only time I worry about severe damage is when we have a really long, wet and mild fall and winter like we had a few years ago. I often think about crane-fly larvae as "natures dethatcher".
One way to easily reduce the populations is to turn off you irrigation in early September. Crane-fly lay their eggs on the lawn and the eggs need moisture to survive. Let the lawn dry out and in most years, it will stay green until September rains start. If it is really hot, you can water it judiciously during the night but infrequently.
Thanks Brian. Excellent info.