"Long before it's in the papers"
December 26, 2012

RETURN TO THE WORLD SCIENCE HOME PAGE

25,000 harmless bugs may inhabit your average Christmas tree

Dec. 26, 2012
Courtesy of the University of Bergen
and World Science staff

Your Christ­mas tree may be adorned with lights and glit­ter. But as many as 25,000 usu­ally harm­less in­sects, mites, and spi­ders are al­so in there, many of them asleep, a Nor­we­gian bi­ol­o­gist says.

“There are a num­ber of in­sects hid­ing in a Christ­mas tree,” said in­sect ex­pert Bjarte Jordal of the Uni­vers­ity Mu­se­um of Ber­gen in Nor­way. Jordal lists spring­tails, bark lice, mites, moths and the odd spi­der as the “creeps” most likely to be dragged in­to the av­er­age house­hold come Christ­mas time.

“There have been found as many as 25,000 in­di­vid­u­al” crit­ters in Christ­mas trees, Jordal said. “If you pound the tree on a white cloth be­fore you throw it out af­ter Christ­mas, you will dis­cov­er quite a num­ber of small bugs.”

So how do they end up in the tree?

“They go to sleep for the win­ter, or hi­ber­nate,” Jordal said. “They usu­ally emp­ty their bod­ies of flu­ids and pro­duce a chilled liq­uid and are com­pletely in­ac­tive. But they re­a­wak­en when the tree is brought in­to the heat of the liv­ing room. It's all down to stim­u­lus. Up­on feel­ing the heat and awak­ened by the light, they be­lieve that spring­time has ar­rived and spring back to life.”

So do they go about wan­der­ing around the liv­ing room or what?

“No, I be­lieve they stay in the tree. Both the Christ­mas tree and the house it­self will be very dry. Al­so, most in­sects don't live off the tree, only in it. As they can­not feed on the lim­it­ed plants found in most house­holds, the bugs will quickly dry out and die. These in­sects and bugs do not con­sti­tute any risk or dan­ger to peo­ple or fur­ni­ture. And if an­yone is wor­ried about al­ler­gic re­ac­tions, I don't think there's any dan­ger of that. But ob­vi­ous­ly, should there be an ex­treme num­ber of mites in a tree peo­ple with se­vere al­ler­gies may re­act to this.”

Are there a fixed num­ber of bugs in every Christ­mas tree?

“This varies a lot,” he said. “Some of it is down to pure co­in­ci­dence and some of it is down to what type of tree it is. Trees chopped in your own back­woods will con­tain more bugs than firs and oth­er trees that have been farmed for use as Christ­mas trees will con­tain few­er creeps. There is par­tic­u­larly much in Nor­we­gian Pine, where­as Ju­ni­per shrub has a fau­na of its own.”

Can you spot the lit­tle beasts?

“No, they are good at hid­ing and are in­vis­i­ble to the hu­man eye, al­though one cer­tainly should be able to spot the odd spi­der. To get a prop­er look, you will have to get out a clean, white sheet and shake the tree.”

Jordal added that it might be a good idea not to let the family dog sleep un­der the Christ­mas tree, due to the pos­si­bil­ity of tick bites. But he said even that is un­like­ly.

Is there a way to min­i­mize the num­ber of bugs?

“A lo­cally grown hard­wood tree” is likely to have fewer “creeps,” Jordal said. “But you should by no means clean or flush the tree free of bugs, as this will dam­age the tree. An­y­way, there is noth­ing to fear. You need to take in­to con­sid­era­t­ion that there are plen­ty of in­sects and bugs in pot­ted plants that are reg­u­lar fea­tures in most house­holds. As we all know, these at­tract plen­ty of flies. It's no dif­fer­ent with Christ­mas trees.”

Are peo­ple aware that the Christ­mas tree they br­ing in­to the house is full of lit­tle bugs? “Probably not,” Jordal said. “After all, these lit­tle bugs are in­vis­i­ble to the hu­man eye. I be­lieve there is a trend in peo­ple not be­ing par­tic­u­larly knowledgea­ble about na­ture. But when you br­ing a tree in­to the com­fort of your liv­ing room, the tree car­ries a part of na­ture with it.”

* * *

Your Christmas tree may be adorned with lights and glitter. But as many as 25,000 usually harmless insects, mites, and spiders are also in there, many of them asleep, a biologist said. “There are a number of insects hiding in a Christmas tree,“ said insect expert Bjarte Jordal of the University Museum of Bergen in Norway. Jordal lists springtails, bark lice, mites, moths and the odd spider as the “creeps“ most likely to be dragged into the average household come Christmas time. “There have been found as many as 25,000 individual“ critters in Christmas trees, Jordal said. “If you pound the tree on a white cloth before you throw it out after Christmas, you will discover quite a number of small bugs. So how do these bugs end up in the tree? “They go to sleep for the winter, or hibernate,“ Jordal said. “They usually empty their bodies of fluids and produce a chilled liquid and are completely inactive. But they reawaken when the tree is brought into the heat of the living room. It's all down to stimulus. Upon feeling the heat and awakened by the light, they believe that springtime has arrived and spring back to life.“ So do they go about wandering around the living room or what? “No, I believe they stay in the tree. Both the Christmas tree and the house itself will be very dry. Also, most insects don't live off the tree, only in it. As they cannot feed on the limited plants found in most households, the bugs will quickly dry out and die. These insects and bugs do not constitute any risk or danger to people or furniture. And if anyone is worried about allergic reactions, I don't think there's any danger of that. But obviously, should there be an extreme number of mites in a tree people with severe allergies may react to this.“ Are there a fixed number of bugs in every Christmas tree? “This varies a lot,“ he said. “Some of it is down to pure coincidence and some of it is down to what type of tree it is. Trees chopped in your own backwoods will contain more bugs than firs and other trees that have been farmed for use as Christmas trees will contain fewer creeps. There is particularly much in Norwegian Pine, whereas Juniper shrub has a fauna of its own.“ Can you spot the little beasts? “No, they are good at hiding and are invisible to the human eye, although one certainly should be able to spot the odd spider. To get a proper look, you will have to get out a clean, white sheet and shake the tree.“ Jordal added that it might be a good idea not to let the family dog sleep under the Christmas tree, due to the possibility of tick bites. But he said even that is unlikely. Is there a way to minimize the number of bugs? “A locally grown hardwood tree“ is less likely to have abundant creepy-crawlies, Jordal said. “But you should by no means clean or flush the tree free of bugs, as this will damage the tree. Anyway, there is nothing to fear. You need to take into consideration that there are plenty of insects and bugs in potted plants that are regular features in most households. As we all know, these attract plenty of flies. It's no different with Christmas trees.“ Are people aware that the Christmas tree they bring into the house is full of little bugs? “Probably not,“ Jordal said. “After all, these little bugs are invisible to the human eye. I believe there is a trend in people not being particularly knowledgeable about nature. But when you bring a tree into the comfort of your living room, the tree carries a part of nature with it.“