Who do you manage Earwigs that have devoured flower and vegetable gardens?
Question:
Earwigs have devoured multiple flower gardens, window boxes, vegetables. There are too many to use rolled up newspaper, hose, cans of oil, etc. I use Neem once/week on zinnias, etc. What about diatomaceous soil? Do I cover my whole two acres of plants and grass and if I do, what is the best way to do it? Or do you suggest something else?
Answer:
Earwigs (Forficula spp.) are an important beneficial predator of many garden pests like aphids, so complete eradication isn’t always desirable, but if their population gets out of control, they can certainly cause a great deal of damage to ornamental and food crops, alike. Judging from the tactics you’ve listed, it sounds as though you have done some reading and tried other approaches. We do still recommend a multi-pronged approach that utilizes traps like newspaper, garden hose, and cans of oil (more information included below), but for 2 acres that approach is obviously not completely effective for a home gardener.
Neem oil is a smothering agent that suffocates insects, but it requires direct contact with the pest (meaning you are really only killing the ones you hit with the oil when you apply it) and it washes off easily with heavy dew or precipitation. Diomataceous earth works by scratching and abrading soft insect bodies that move across it, dehydrating the pests, but like neem it is rendered ineffective by the first good rain you get. Neither of them is likely to be an effective strategy over 2 acres by hand.
One other important aspect of earwig control to mention is cultural control and sanitation. Earwigs like to hide in mulch, tall grass, nearby brush, garden tools left out, kids’ toys, etc.–anything they can hide under to make a nest. Unsurprisingly, conscientious removal of this material is crucial to managing the earwig population. For a critical garden element like mulch, you obviously don’t want to remove it entirely, but you might need to scout it regularly and replace it often until the problem is under control.
Assuming you continue to pursue these tactics, your next option is chemical control. As you will read in the resources below, pyrethrins and spinosad are both effective and combating earwigs, and are the least harmful pesticides as you begin to move into heavier substances than neem and diomataceous earth. If you choose to go this route, remember to always read carefully and follow diligently all instructions on the label. More is not better.
Utah State Univ Extension suggestions for dealing with earwigs
Univ of CA page on earwig management
I’m hopeful that adding the pesticides to the other tactics you are employing will eventually deal with the situation.