Bugs in Christmas Tree: What They Are and What to Do

Bugs in a real Christmas tree are usually overwintering insects that wake up once the tree warms up indoors. The most common are large brown or black Cinara aphids, tiny spruce spider mites, praying mantis egg cases, adelgids and the occasional small spider or bark beetle. Extension entomologists at NC State, Penn State and Oklahoma State agree they are a nuisance, not a danger: they do not bite people or pets, carry disease, or infest your home. Shake the tree before it comes inside, vacuum any strays, move egg cases outdoors, and skip aerosol bug sprays near the tree.

Why a Christmas tree can bring bugs indoors

Real Christmas trees grow outdoors, often next to woods and fields, and they give insects a sheltered place to spend the winter. Oklahoma State University Extension notes that it is not uncommon for a tree to harbor ants, bark beetles, aphids, beetle larvae, praying mantises or spiders that settle in on branches or under the bark in the fall.

While the tree is cold, these insects stay dormant and are hard to spot. Once it is set up in a warm living room, NC State Extension explains, they behave as if spring has arrived. Some simply wander toward windows and lamps, and a few, such as aphids and spider mites, can even reproduce on the cut tree.

The good news is that it is rare. NC State’s Christmas tree specialists estimate that in most years perhaps one tree in 100,000 carries any one of these pests, and problems tend to be worse after an unusually warm, dry fall.

Common bugs found in Christmas trees

Cinara aphids

These are the bugs most people notice. Cinara aphids are much larger than garden aphids and are brown to black, so they are often mistaken for ticks. NC State points out the easy difference: aphids have six legs, while adult ticks have eight. Cinara aphids feed only on conifers, will not feed on your houseplants, and do not bite or carry disease. On a warm indoor tree they can produce live young, so numbers can build quickly. If you are not sure what tiny insects you are looking at, our comparison of aphids vs. fungus gnats covers how aphids look and behave.

Spruce spider mites

Spider mites are very small and look like dark red dots when shaken out of a tree. NC State notes they can leave small red stains on carpets, ornaments and furniture and may make needles drop early, but they cannot live in your house. Once the tree goes out, they die off.

Praying mantis egg cases

A mantis egg case is a tan, foamy-looking mass about the size of a walnut, stuck to a branch. NC State says a female lays 200 to 400 eggs in the fall, and the warmth indoors can trigger hatching, releasing dozens of tiny mantids. Mantids are beneficial predators in the garden, so Oklahoma State recommends cutting off the branch and placing it in a sheltered spot outside, where it should hatch in spring.

Adelgids and scale insects

If you see white, cottony “flocking” on twigs or bark, Penn State Extension says it is probably adelgids, tiny sap-feeding insects that stay on the tree. Both the insects and their wax are harmless. Scale insects look like small bumps on needles or bark. Their tiny young, called crawlers, may wander off the tree briefly, but they can simply be wiped or vacuumed up.

Bark beetles, spiders and other strays

Penn State notes that small, cylindrical brown bark beetles can sometimes emerge from a tree that stays indoors for a long time, often leaving fine sawdust near tiny holes. They feed on stressed or dying trees and cannot infest the dry, finished wood in your home. Small spiders, which hunt the other insects, may also drift off the branches. Penn State adds that low indoor humidity and the lack of suitable food mean these strays usually die within a short time.

Are bugs in a Christmas tree dangerous?

No. NC State Extension says these hitchhikers do not bite or cause disease and calls them “just a nuisance.” Penn State Extension adds that, because they live on conifers, none of the species that come in on a real tree are dangerous to the home, its contents or the people in it. The main practical risk is staining: crushed aphids can leave purple or red marks, and spider mites can leave small red spots.

How to check a tree before bringing it inside

Inspect the branches. Look along the trunk and the undersides of lower branches for egg cases, clusters of dark aphids, white cottony patches or fine sawdust. Oklahoma State notes the foliage should look clean, not sticky.
Shake it hard. Many lots have mechanical tree shakers. Penn State notes that shaking dislodges many insects, especially adults. NC State suggests shaking it again at home before it comes inside.

Consider rinsing it. NC State suggests spraying the tree with a garden hose and letting it dry before bringing it in. Any pests present will usually fall out.
Remove egg masses and nests. Cut off branches holding mantis egg cases and put them outside. Penn State also advises scraping off other egg masses and removing old bird nests, which can carry bird mites.
Let it settle in a garage first if you can. A day in an unheated garage or porch gives you another chance to spot movement before the tree is decorated.

What to do if bugs show up after the tree is inside

Vacuum, don’t squash. NC State recommends a hose attachment without a beater bar, and warns against mashing aphids on carpets or upholstery because they can stain. Empty the vacuum outdoors afterward.
Skip the aerosol sprays and foggers. Penn State advises limiting control to non-chemical methods, noting that aerosol insect sprays are often flammable, are usually not labeled for indoor use and should not be sprayed on a Christmas tree. A tree covered in electric lights is the last place you want a flammable spray. Our article on whether foggers kill flies explains why bug bombs rarely solve indoor insect problems anyway.
If you do treat, read the label. NC State lists insecticidal soap as the least toxic option. Unplug the lights first, use only a product whose label allows the use, and follow EPA’s advice to read and follow the entire label.

Move or return a badly infested tree. If numbers keep climbing, NC State suggests taking the tree out of the house or asking the seller to replace it.
Leave the ornaments alone. NC State notes the insects won’t stay on your decorations until next year.

Other bugs you might notice in December

Not every insect you see around the holidays came in on the tree. Large, slow flies buzzing at sunny windows are often cluster flies that moved into the walls or attic in late summer. If you are seeing lots of flies all at once, our guide to lots of flies in the house suddenly walks through how to find the source.

Boxes of decorations stored in attics and garages are also favorite nesting spots for mice. If you find droppings or chewed paper when you bring the boxes down, see our guide to mice in walls for how to confirm and handle a rodent problem.

Should you switch to an artificial tree?

Not because of bugs. NC State’s specialists point out that the odds are against ever having this problem again, and that hitchhikers are often a sign of a freshly harvested tree. A quick inspection and a good shake take care of most issues.

FAQ

What are the tiny black bugs in my Christmas tree?

Most often they are Cinara aphids, which are large for aphids and brown to black. Count the legs: aphids have six, while ticks have eight. NC State notes ticks have never been found on Christmas trees in western North Carolina.

Can bugs from a Christmas tree infest my house?

No. The insects that come in on a tree depend on living conifers. Penn State Extension explains that dry indoor air and the lack of suitable food mean they usually die within a short time, and spider mites die out once the tree is removed.

Do Christmas tree bugs bite?

No. NC State Extension says aphids, spider mites and mantids from Christmas trees do not bite people or pets and do not carry disease.

Can I spray my Christmas tree with bug spray?

It is not recommended. Penn State Extension warns that aerosol insect sprays are often flammable, usually not labeled for indoor use and should not be sprayed on a Christmas tree. Vacuuming is the safer first step.

What should I do with a praying mantis egg case on my tree?

Cut off the branch and put it outside in a sheltered spot, such as a shrub or the edge of the yard. Oklahoma State Extension notes it should hatch in spring, and the mantids will help control garden pests.

Sources

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