A number of arthropods live on Christmas trees while others may use them for winter shelter. Most are inactive or sluggish at outdoor temperatures but become active when their tree is brought indoors.
The awakening can cause some alarm but usually poses only a temporary nuisance. It is best to deal with these accidental invaders by swatting, spraying directly with insecticidal soap, or wiping up with a soapy rag. Do not spray ready-to-use insecticides indiscriminately or set off “bug bombs” to deal with the problem.
Here are some common culprits:
White Pine Aphids
Colonies of white pine aphids (Figure 1) are common on shoots and branches of eastern white pine and Scotch pine. Wingless aphids crawl while winged adults may fly. These soft-bodied insects are sap feeders. They will not become established household pests.
Pine Needle Scale
Pine needle scales (Figure 2) are sap-feeding insects that prefer Mugo and Scotch pine but can live on other pines and spruce. Infestations of narrow, white waxy scale coverings are very apparent on needles of infested trees. These coverings protect a batch of eggs that normally hatch in spring. The tiny red crawlers may become active on trees that are indoors for a long time. They pose no threat to houseplants and can be wiped up with a soapy cloth.
Figure 1. Aphids on pine (Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org)
Figure 2. Pine needle scale (Photo: Lee Townsend, UK)
Praying Mantid
Even though praying mantid eggs (Figure 3) can survive a long, hard winter, they hatch relatively soon after being brought indoors. Scores of tiny mantids will crawl around looking for prey, usually consuming any siblings they encounter. Tap the small mantids into a container of soapy water or trap them on sticky tape exposed on branches where they are active.
Spiders
Many spiders spend winter as eggs in masses protected by coverings of silk. Sufficient exposure to warm temperatures can stimulate egg hatch and tiny roaming spiders exploring their new world. The same remedies for newly hatched mantids will help to reduce spider numbers relatively quickly.
Figure 3. Praying mantid egg cases (Photo: Lee Townsend, UK)
Figure 4. Spider egg case (Photos: Lee Townsend, UK)
Rough Stink Bugs
Some species pass winter as inactive adults on tree trunks and other similar sites. Often they are larger than the other common tree dwellers but pose no problem other than some temporary anxiety.
Figure 5. Rough stink bug adults send the winter on tree trunks (Photo: W. Cranshaw, Colorado State University, Bugwood.org)
Identification and Management
You can get help with insect identification and management recommendations at your local Cooperative Extension Service office.
By Lee Townsend, Extension Entomologist
