December 9, 2010 at 2:34 p.m.
Adelgids attack the bark on pines, especially white pines. The adults are tiny with soft, cottony outer coverings that create a white, fluffy appearance on the stems of the tree. They become active when the temperature reaches fifty degrees or when brought into the home. They should be noticeable when you purchase the tree, since they are host specific, they don't transfer from the Christmas tree to the houseplants.
Aphids are small sucking insects that are also host specific and don't feed on houseplants. Spider mites often become active when the temperature rises, as it does in a home. They are very small and may cluster together with some webbing present. They generally remain on the tree when active since they can't fly, but can become a pest on houseplants when too close to the tree. Spiders sometimes seek shelter under the bark of Christmas trees. Although rare, they can be brought indoors and eggs that are present may hatch, but are not dangerous to humans or pets.
Most retail Christmas tree outlets use mechanical shakers to remove dry and damaged needles. Shaking also dislodges many insects or spiders living on a tree. However, some may remain and be brought indoors. Check your tree once you bring it in and remove any insects you find on the tree. If you miss some, use a vacuum cleaner under the tree to remove the rest. Pesticides are not recommended and never use flammable types of pesticides around conifer trees.
Houseplants brought in from outside and plants given as gifts or self-giving may add to the unwanted list of insects and diseases. Houseplants that come from a nursery or garden center have been grown under ideal conditions. According to Deb Brown, keep close attention to the changing health of your plants. A small magnifying glass will help spot mites and other insects that have made their way into the home.
One way to help keep plants healthy is to keep the foliage clean. A layer of dust interferes with the light penetration, which can be a problem with shorter and less sunlight during the winter. Use a soft, damp rag to wipe the upper and lower surfaces of the leaves along the stems. If it has too many leaves, prepare a sink full of lukewarm water with a few drops of dishwashing liquid. Seal the soil surface of your plant with aluminum foil, then turn the plant upside down and swish it through the water.