The European earwig (Forficula auricularia) may be difficult to appreciate because it is an invasive species with menacing rear-pincers, and the name “earwig” is creepy. However, what role do they play in agricultural settings like orchards? Among orchardists interviewed in Central Washington, the majority were unsure of the role earwigs play in the orchard ecosystem.
To address this uncertainty, several experiments were designed. The conclusion: The European earwig is an underappreciated biological control agent and likely a beneficial insect in most apple orchards.
European earwigs are commonly found on damaged apples, but the question arises: Did earwigs cause the damage, or are they merely sheltering in existing damage because of their preference to aggregate in tight spaces? This question was addressed by assessing fruit damage in control plots compared to plots where thousands of earwigs were released. It was found that earwigs do occasionally damage apples when confined with them in the lab, but in field conditions, there was no correlation between fruit damage with earwig densities. In relatively soft fruit like peaches, earwigs are pests, but apples may be too hard for earwigs to easily attack.
Earwigs are also generalist predators, capable of eating a variety of insect pests. Their predatory behavior is difficult to observe due to their nocturnal behavior, but experimental evidence shows European earwigs contribute to woolly apple aphid and green apple aphid (Aphis pomi) suppression. More research is needed to assess their importance in suppressing other pests across crop systems.
Sharing earwig behavior with apple growers might help improve the image of these charismatic and potentially beneficial insects. So, while they are not likeable in all aspects, the European earwigs are indeed fascinating and economically important animals.
Read more about this research at entomology today.