The likelihood that you’ll welcome pests into your home when you bring in your living Christmas tree is minimal, but not impossible. Occasionally, living Christmas trees can harbor overwintering insects, insect eggs or other arthropods that could become active when exposed to warmer indoor temperatures.
You can have a bug-free Christmas by knowing what kinds of common pests to look for, how to prevent bringing them inside and what to do after they’ve invaded.
Before the tree is indoors
Before bringing your tree indoors and exposing it to warmer temperatures, make sure you check it for signs of insects, spiders and other pests. Many arthropods found in Christmas trees will either be adults or eggs. Make sure to check for both. You can dislodge adults that may be hiding in your tree’s branches by using a mechanical tree shaker or vigorously shaking your tree before leaving the retail lot of Christmas tree farm. You can remove many types of egg masses by scraping them off the tree trunk or branches. Lastly, you want to check for old bird nests. Although some consider them to be good luck, they can contain mites and should be removed before bringing your tree indoors.
After the tree is indoors
Once your tree is indoors, Penn State University Extensions recommends leaving the insects found on the tree alone until it is removed from your home. For insects that may have strayed to ceilings, walls or windows, eliminate them with the vacuums cleaner. These bugs won’t be around for long regardless of what you do to manage them. They have a hard time surviving in indoor environments during winter due to low humidity caused by heating sources and a lack of food sources.
Penn State Extension, also stresses that you shouldn’t use chemical products, and especially not aerosol insect sprays as a means of control. They are flammable and, generally, not labeled for indoor use. Do not spray chemical insect repellents on your Christmas tree.
9 pests to watch for
As stated above, most living Christmas trees will be free of arthropods, but not all. In Pennsylvania, Ohio and surrounding states, there are 9 common pests to keep an eye out for before bringing your Christmas tree indoors.
Spotted lanternflies are a relatively new, but incredibly invasive pest. Since being discovered in 2014, the spotted lanternfly has spread to 13 counties in southeastern Pennsylvania, three counties in adjacent New Jersey and one county in Virginia. While quarantines are set up to prevent the spread of the spotted lanternfly, if you purchased your Christmas tree near one of the quarantines counties, it’s probably still a good idea to check your tree for eggs masses before transporting it. Inspect the branches and trunk of your tree for crusty, grayish smears. Then, scrape them off into a plastic bag with rubbing alcohol and dispose of them. For more on finding and destroying egg masses read, How to identify and destroy spotted lanternfly egg masses.
Residents near the spotted lanternfly quarantine zone are also encouraged to dispose of Christmas trees via community tree recycling programs to prevent any overlooked, unhatched egg masses from hatching in the spring and spreading the spotted lanternfly.
If you live outside of the quarantine zone and spotted lanternflies hatch indoors from a Christmas tree, please report the incident to the PA Department of Agriculture if you live in Pennsylvania. Non-Pennsylvania residents should report incidents to their state agricultural agency.
If you notice white “flocking” on needles, twigs, or bark, it probably has adelgids. Adelgids are tiny, aphid-like insects that feed on plant sap and secrete cottony wax filaments around their bodies. They are usually primarily found on white pine and occasionally on Scotch and Austrian pines. The flocking they produce are harmless and they will not leave your tree. It’s best to just let them be until the end of the holiday.
There are 152 species of aphids in North America and they can be found on most species of conifer. They come in shades of black, grey and brown with long legs. The first generation that hatches is wingless, but if your tree is indoors for an extended period of time — if you have a live tree with a root ball that you plan on planting when the ground thaws — aphids may reproduce a second generation of winged offspring. Because many aphids usually prefer a specific host, they will likely stay around the tree until the needles begin to dry out and they need to search for a new host.
Bark and ambrosia beetles feed on stressed, dying, and dead trees. In their larval stage, the beetles bore through branches or trunk of a tree, which may create a very fine sawdust that is pushed out of tiny holes. The best way to tell if your tree has been invaded is to look for signs of sawdust. If you bring an infested tree home and adult beetles emerge, they will likely die in a short time as they are intolerant to low air humidity.
Overwintering mites can become active when exposed to warm weather; however, they will likely stay on the tree where they can prey on insect and mite eggs. Fortunately, none of the predatory mites associated with Christmas trees pose a threat to people or pets.
Check your tree for brown, puffy eggs masses attached to twigs or branches. If you accidentally bring one indoors on your Christmas tree, the egg mass will hatch after several weeks, releasing dozens of babies. These babies will likely eat each other when this happens due to a lack of food. The best control method is to find the egg mass before it’s indoors, remove it and leave it in a shrub or other plant outdoors to hatch in the spring.
Bark lice are small soft-bodied, grey or brown insects with wings. They feed on fungus, mold, pollen, algae and dead insects that accumulate on the bark and leaves of the trees they’re living on. Although their name contains the word “lice” they don’t bite or feed on people. Bark lice require high humidity and will quickly die indoors.
Scale insects are usually covered by a waxy coating and do not move. The most common scale insect found on Christmas trees are pine needle scales. Adult females are are found on pine needles, measuring approximately 1/8 inch long, covered by a white waxy cove. Pine needle scales overwinter as eggs under a mother scale’s cover. However, can emerge as crawlers when a Christmas tree is brought indoors. Crawlers are tiny red bugs that can appear in large numbers. if crawlers emerge, Penn State Extension recommends cleaning them up with a damp towel.
Spiders found on Christmas trees are predators of the insects you may potentially find on them. They are not dangerous to people or pets. They are either overwintering species that have become active or spiderlings that have hatched after being exposed to warm temperatures. Most of the time, these outdoor species will die in a short time due to an inability to survive indoors.
Pests can live on artificial trees too
Don’t be turned off of purchasing a real tree because of the possibility of tiny pests. Control methods are relatively simple and low maintenance. And remember, artificial trees can house pests, too. For more on this topic, check out a recent column written by Kymberly Foster Seabolt where she hilariously details a run-in with a squirrel as she unpacked her Christmas tree this year — Christmas critters and tiny trees.
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