A number of yellowing Jeffrey pine trees along Pioneer Trail in Meyers are the work of “needleminers,” a native insect that feeds on their needles, the Forest Service said on Thursday.

Needleminers eat their way through the middle of the needle, causting it to die and turn yellow, or, in extreme cases, red. Only when all the needles on an infested tree turn red does it mean the tree has died.

“Although the trees look as though they are severely damaged, more often than not they will recover once there is a reduction in the needleminer population,” the Forest Service said.

Needleminer infestations usually are kept in check naturally. Jeffrey pines are more susceptible to the insects when under severe stress from drought. Infestations can cause the trees to lose strength and succumb to other pests, such as bark beetles.

“While the infestation appears to be contained to small segments of Pioneer Trail, it is possible for the needleminers to spread to other parts of the basin. Forest Service personnel are monitoring the situation, and the extent of the outbreak will be determined later this summer during an annual aerial survey flight,” the Forest Service said.