If your household celebrates Christmas and prefers to do it with a natural tree, you may end up bringing in more than just a beautiful evergreen. There are several kinds of insects and arachnids that may be hiding on the needles and twigs of your delightful décor.
Some of the invaders with Yuletide spirit include pine adelgids, aphids, scale insects, and spiders. One of the more interesting insects that may crash your Christmas gathering is a praying mantis. These hitchhikers usually enter the home as eggs, which is the normal overwintering state for many arthropods. Mantids specifically, create an ootheca, an egg case that looks like spray foam insulation and protect their eggs. These can be on the trunk or twigs of a tree and hard to spot.
Regardless of species, eggs gradually develop as the winter thaws into spring. This is through the accumulation of degree days: certain days in which the temperature reaches a threshold that allows for development. Indoors, however, they will accrue degree days much faster and eggs can hatch during the Christmas season, possibly leading to hundreds, even thousands, of tiny critters running around your gifts. None of the mentioned arthropods pose a hazard to homes, pets, people, or stocking stuffers though. You can always easily vacuum them up and dispose of them.
You may also find some adult insects and spiders that are hiding in the tree. Stink bugs are one possible example that could be using the tree as their winter home. Bark beetles are another possibility and would emerge as adults from the wood of the tree. The larvae of these small beetles (1/4 inch or less long as adults) live and feed in wood. Usually they overwinter in the trunk and emerge as adults the next season. The warmth of hearth and home, though, will cause them to emerge much quicker than usual. Even though they utilize wood, these beetles will not be interested in infesting the lumber of your home.
All in all, these accidental house guests may be alarming but shouldn’t cause much concern. Vacuuming, spritzing individuals with soapy water, or sweeping them outside are all acceptable responses. Bug bombs, liquid sprays, or other insecticides should not be used on the tree. These residues could be hazardous to people and are not likely to control any of the mentioned bugs.
By Jonathan Larson; Extension Entomologist