MUNsolved Mysteries


(Gazette, Jan. 9, 1997)

Have a burning question pertaining to science, engineering, medicine, the arts, music, humanities, social sciences, physical education, or any other field? Let us know; we'll do our best to find the answers for you, drawing upon the expertise of members of the university community.

We recently heard from Joyce Nevitt, a reader from St. John's, who wrote about a creepy-crawly subject:

"I have a question for which I've long wanted to find the answer. What use are earwigs? How do they breed? One never sees a web or coccoon, or other such evidence, yet it seems that suddenly they appear as if from nowhere! Do they nest? If so, how can their nests be identified and destroyed? It seems that nature has a purpose for all its creatures -- but earwigs?"

Dr. David Larson of the Department of Biology agrees that all insects have a purpose, though the purpose may be of no benefit to humans.

"I think earwigs have a use in us," he said. "Without our warm buildings I don't think they could survive a Newfoundland winter."

Dr. Larson said that small, black European earwigs set up shop in Newfoundland in the late 1940s. (For the record, another animal, shiny brown and fast-moving, which can be found under rocks and in turned up soil and is referred to by many Newfoundlanders as an earwig, is not an earwig at all, but a centipede.)

European earwigs first appeared in this province in St. John's, but they're slowly spreading across Newfoundland from community to community. They are omnivorous creatures which feed mostly on plant material such as fungal spores, algae, lichen, detritus of higher plants, as well as the fresh parts of flowering plants. But also, a significant portion of their diet is small insects.

"You won't see coccoons or webs with European earwigs because they don't use them," Dr. Larson said. "In the spring the female will make a tunnel in the soil and lay her eggs there. She's a good parent; she broods the eggs, stays with them till they hatch, then feeds the small earwigs until they are big enough to move out on their own. The earwig's pincers probably have several uses. Large adults have wings which fold tightly against their backs, and the pincers may be used to fold the wings into place. Males have larger pincers than females, which suggests they are also used during sexual displays when males compete for females. The pincers may be used as defense against other insects that feed on earwigs."

Most people see European earwigs indoors in the fall, when the insects seek out a warm place to hibernate for the winter. They may be unwanted visitors but they're harmless. Many people try to eradicate them, but they are hard houseguests to get rid of because they tend to hide in dark cracks and so elude the poisons set out for them. Never fear, though, they won't breed in the house, and their pincers -- though ferocious looking -- aren't generally strong enough to pierce human skin.

"They don't really cause us any problems," Dr. Larson said. "Sometimes they'll do a little bit of damage to gardens -- they'll chew on a rose blossom or some fruit -- but not really anything serious."

Is there a question bugging you? Write to MUNsolved Mysteries, Gazette, Arts and Administration Building, Memorial University of Newfoundland, St. John's, Nfld., A1C 5S7; e-mail gazette@morgan.ucs.mun.ca, or fax 709-737-8699. Please include your name and telephone number.