The earwig is a highly prevalent insect in our country, and its classification as a parasite depends on the specific environment it inhabits. It is commonly referred to as scissor, scissor cutter, and pincer, but its scientific name is Forficula auricularia, derived from the Latin term auricularia, meaning relating to the ear. This nomenclature is linked to a particular legend: it is believed that these insects enter the human ear and, as they navigate, lay eggs in the brain, giving rise to colonies. This imagery, however, is purely a legend. In reality, earwigs are entirely harmless to humans.
Nevertheless, they pose a threat to certain crops as they feed on fruits, both while still on the tree and after they have been harvested. Interestingly, in specific scenarios, they serve as useful insects by acting as natural predators for other crop parasites.
Description of the Earwig Insect
The Forficula auricularia is an insect belonging to the order Dermaptera, family Forficulidae. It is native to Europe but is now also widespread in the Americas. These insects are small, ranging from 10 to 15 mm in length. They have elongated, flat bodies with three pairs of legs, brownish in color, and a shield-shaped pronotum. The distinctive feature is their forceps-like cerci, from which they get their common name. These terminal forceps serve three functions: mating, feeding, and self-defense.
There are differences between males and females. Male earwigs have sturdier, wider forceps with crenulated teeth, while females have weaker, straight forceps.
Biological Cycle of the Earwig (Forficula auricularia)
Female earwigs overwinter in small nests dug into the ground, where they lay up to 50 eggs. Nymphs hatch in the middle of winter and disperse in the environment with the first warm spring days. The new adults develop in late spring.
Earwigs are highly resilient insects, tolerating both low and high temperatures. They prefer humid places like cracks in tree bark, under flowerpots, rotten tree trunks, stones, and soil crevices near plant stems. Earwigs are nocturnal and avoid light. They can also seek refuge indoors, commonly found near sinks, bathrooms, or kitchens. They can infest homes due to their gregarious behavior.
Earwigs are omnivorous insects. They primarily seek decomposing plant material or fresh fruit but also prey on other small insects. Consequently, they can be considered both pests and beneficial insects, depending on the environment they inhabit. For instance, they feed on aphids, psyllids, codling moths, or scale insects, which are significant crop pests. Therefore, in a garden infested with aphids, earwigs serve a purpose similar to ladybugs.
Damage Caused by Earwigs
Earwig damage primarily affects very sugary fruits, such as apricots, peaches, and plums. The insects enter ripe fruit just before harvesting and feed on the pulp. They can also be found on already harvested fruits, which are softer and thus easier for the earwigs to penetrate to the pit.
How to Catch Earwigs
Forficula auricularia is considered a secondary pest. Artisanal mass trapping systems are used for biological defense. Essentially, artificial shelters like pieces of cane, corrugated cardboard rolls, or small wooden boxes are placed on fruit trees at risk. Earwigs seek refuge in these shelters during daylight hours, making it easy to remove them when they aggregate. These artificial shelters are set up from early May when typical spring fruits begin to ripen. The traps are highly effective because earwigs emit aggregation pheromones, attracting other earwigs.
Why Not to Kill Earwigs
Earwigs should not be eliminated due to their vital role as active predators of other crop pests. They can simply be kept away from orchards. Prolonged trapping may result in the insects being released back among the trees after harvesting. This is a principle of biological control, safeguarding both crops and the ecosystem. Artificial shelters can also be placed near homes to prevent the insects from entering houses.
Preventing Earwigs from Climbing Trees
If earwig infestations are high, trees can be protected from potential attacks. The goal is to prevent the insects from reaching the fruits. Smearing a band of sticky material, such as classic tree band glue (like this one), on the main trunk is one method. The sticky substance should also be brushed on any support stakes or ties. Tall grass can also serve as an excellent bridge for the insects. Keeping it low, therefore, by following a rational weed management approach, is a good practice.
Frequently Asked Questions
Are earwigs harmful to humans?
No, they are entirely harmless to humans. Despite a prevalent legend, they do not lay eggs in human brains and are not a threat to people.
What crops do earwigs typically target?
They primarily feed on fruits, especially those with high sugar content, such as apricots, peaches, and plums. They can enter ripe fruits and consume the pulp.
Can earwigs be considered useful insects?
Yes, they can be beneficial in certain situations. They act as natural predators, feeding on other small insects like aphids, psyllids, and caterpillars, making them useful for pest control in gardens.
How can I protect my fruit trees from earwig infestation?
To prevent they from reaching the fruits, you can apply a sticky material like tree glue around the main trunk and support poles. Keeping the surrounding grass short also reduces their access to the trees.
Is potassium bicarbonate effective in deterring earwigs?
Potassium bicarbonate is not specifically known to deter earwigs. Its common uses include acting as an acidity regulator in the wine production process and as a fungicide in agriculture.
How can I coexist with earwigs without harming them?
Instead of eliminating they, consider using natural methods like creating shelters away from your crops or placing them near your house. This allows them to live peacefully while minimizing their impact on your garden.
Can earwigs infest homes?
Yes, earwigs can enter homes, especially in damp areas like bathrooms and kitchens. Proper sealing of cracks and crevices can help prevent their entry into living spaces.
When should I use mass trapping for earwigs?
Mass trapping with artificial shelters is effective when fruit-bearing trees are at risk. These traps can be placed around the trees in early May when spring fruits begin to ripen, attracting and trapping earwigs effectively.