Many of the phone calls Christmas tree farmers receive around the holiday season concern Cinara aphids. These aphids are large (among the largest aphid species in the world), dark-colored, and can be found on numerous coniferous species. A handful of native and invasive Cinara species exist in North America, and species identification can be tricky.

Cinara aphid colonies on Christmas trees produce a sticky honeydew that can reduce photosynthesis and provide a substrate for unsightly sooty mold fungi. However, these insects normally do not harm trees. They are completely harmless to humans and do not sting or bite. Cinara aphids produce live young during part of their complex life cycle. Cinara aphids can also survive subfreezing temperatures and become more active when they are moved indoors, and sometimes will produce live young while on trees brought indoors. People are understandably reluctant to encounter insects on their live Christmas trees. Therefore, identifying and removing colonies or individual Cinara aphids before a tree is sold is preferable. Dr. Sidebottom has an excellent article on Cinara aphids.

Cinara eggs are not often seen in WNC. However, we have recently noticed Cinara eggs on trees in October and November. In species such as Cinara strobi and Cinara pini, eggs are laid in the fall and hatch in the spring. Previous efforts to hatch Cinara aphid eggs on trees moved indoors have proved unsuccessful and aphid colonies can move relatively quickly from tree to tree. Therefore, these eggs serve as a reminder to check and/or treat your trees before sale to avoid Cinara adults and live young catching a ride in your cut trees.