Although little real injury to the health of the infested tree results from pine tip moth attacks, tree growth can be delayed and the form altered to a bushier appearance. Tip moth injury can be diagnosed during early to midsummer by examining suspect shoots that have dried and shriveled. At this time, the damaging stage of the insect or old discarded skins can be detected. If the insect is not present, examine the damaged terminal growth to see if there is evidence of the internal tunneling typical of most tip moth injuries. A different set of tip moths infests pinyon pine.
New infestations originate with eggs laid by the adult female moths, one generation per year.
May. Eggs hatch about the time new shoots emerge from buds. The tiny larvae immediately begin to bore into the fresh young shoot tissue. The larvae feed and grow within the developing shoots through May, June and July, causing tip growth to die back beyond the feeding site. Tip damage from larvae of pinyon pine tip moths. When feeding is completed, the full-grown caterpillar leaves the shoot to crawl down the trunk.