Unwanted 'Presents' Under And On The Christmas Tree - by Michael Waldvogel and Patricia Alder

Most of us are familiar with aphids which are the small, often greenish colored insects that feed on a wide variety of plants. They leave the deposits of sugary honeydew on foliage that attract ants. Aphids have piercing-sucking mouthparts that they use to pierce and suck the juices out of plants.

Cinara conifer aphids (Photo: Whitney Cranshaw)

Cinara aphids (i.e., in the taxonomic genus Cinara) are among the largest aphids. They are 1/8"-1/4" in length and their bodies vary in color from green to brown to black and many have distinct markings. Most aphids are wingless but at various times of the year, winged individuals will appear within a given generation.

The Cinara aphids are also called "Cinara conifer aphids" because they attack a wide variety of conifers (pines, spruces, firs, etc.) and are typically species specific, i.e., a particular species of Cinara aphid will attack a particular species of conifer.

So, why are we talking about aphids now? We don't tend to see aphids in the winter, right? That's mostly true, but many of us have already or will be purchasing Christmas trees this holiday season, and guess what? These aphids are commonly found on Christmas trees. Once the tree has been decorated and is sitting in the living room near the warmth of the open fire where you've hung your stockings with care, the aphids become active and will often drop from the branches and onto the floor, gifts, cat, etc. that are beneath the tree. People often wonder if these aphids bite. Fortunately, you have nothing to worry about, unless you're a Fraser (not "Frasier") fir.

So what do you do if you end up having these unwanted critters on your Christmas tree? Just vacuum them up, but don't suck up that ugly dough ornament that your kid made in the 2nd grade; he/she will never forgive you for it even though you've been looking for an excuse to trash it. Don't squash the aphids, as they may leave a purplish stain.

As for spraying pesticides - if you "Google" 'Cinara', you'll stumble across a publication on another NCSU website (not mine) that suggests setting off a fogger in the room or spraying the affected tree with any common household insecticide (after unplugging lights and any electric ornaments). I have had a discussion with the author previously about this advice because I think fogging will not kill the aphids on a decorated tree and spraying the branches with 'Raid', 'Enforcer', etc. is a bad idea. Why? Who is likely to come into contact with those lower treated branches (and now-contaminated ornaments) - little kids and pets (admit it, you've all seen a cat hack up a hairball with tinsel in it, not to mention the glimmering dog poo in the backyard).

A colleague of mine has pointed out an instance (not in NC) where a homeowner became irate at finding these aphids streaming off of his tree. He dragged the tree out of his house and in the process, injured himself. Yes... he sued the Christmas tree grower (and probably the poor guy who operated the sales lot near his house).  And yes… he was successful! As a result, my colleague recommends treating the trees. That’s fine for her to recommend to the growers but I have extreme reservations about certain types of treatments for trees that are being used indoors as Christmas trees (as I mentioned above).

We’ve seen plenty of such inane lawsuits, but if you feel you must spray something, use insecticidal soap. You can buy one of the commercial products such as "Safer" brand. You can try making your own batch using a liquid soap or even a pure Castille soap. Mix one teaspoon in a quart of water and apply it in a spray bottle. Do not use one of those extra strength, grease-cutting detergents because they might discolor the tree needles. And yes... the obvious - unplug the lights before spraying and let everything dry before turning the lights back on. Even if you use the soap solution, the effectiveness will likely be limited by the amount of decorations that you have on the tree that quite obviously impede the dispersal of the spray.

If all else fails, just remember that this is temporary (the aphids will leave when the tree does). Try to ignore the aphids, drink some 1000 calorie egg-nog with or without alcohol (the latter will help with ignoring bugs on the Christmas tree) and you should enjoy the holiday quite nicely!