Other types of aphids can also be a problem. Bagworm lives in a two to three inch long sack built from needles. The insect overwinters as an egg in the sacks of the females. The injury consists of feeding on the foliage with most of the injury near the top of the tree. Control by hand-picking the bags in winter.
Spider mites cause older needles to lose green coloration and become yellowed.
The insects are very small and difficult to see so infestations can become severe before being noticed. This information is for educational purposes only. References to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. This information becomes public property upon publication and may be printed verbatim with credit to MSU Extension. Reprinting cannot be used to endorse or advertise a commercial product or company.