Most of them make a quick exit if they can, but a few insects are so closely tied to the plants they are on, they may come inside. After the tree is trimmed and the holiday decorations are hung, two of the most common insects discovered are pine aphids and praying mantids - mantids is the plural of mantis. Often pine aphids fall from Christmas trees when trees are brought into the home, or when they are removed after the holidays.
Aphids are common plant pests that feed by sucking plant fluids.
They are not harmful to people, structures or pets. Check for aphids on plants and in room areas where Christmas trees are displayed. Often, aphids can be removed by hand or by vacuuming. If you do vacuum, place the vacuum bag in a plastic bag and dispose in outdoor trash when you are finished. The other common stowaways often found on Christmas trees are praying mantis egg cases.