Evaluating the post-harvest survival and emergence of elongate hemlock scale from Fraser fir Christmas trees.

The elongate hemlock scale (Fiorinia externa Ferris; Hemiptera: Diaspididae) is an invasive insect that originated in Japan and was first detected in North America in Queens NY in 1908. It has since become a significant post-harvest pest of Fraser fir (Abies fraseri [Pursh] Poir.), posing regulatory problems for the North Carolina Christmas tree industry which produces trees that are sold and moved across the country. Observations by specialists suggest that crawlers, one of two mobile stages of the insect, can emerge from eggs on host material for an extended period, potentially spreading this scale to new areas. However, research into crawler emergence under variable conditions, as well as the duration harvested Fraser fir can sustain live egg-producing adult female elongate hemlock scale (and thus prolong crawler emergence) is lacking. Therefore, we evaluated these insects' post-harvest activity on cut Fraser fir. In our first study, we evaluated weekly crawler emergence from Fraser fir trees and branches between two post-harvest treatments (baled and unbaled) under constant conditions for 7 wk. The second experiment aimed to simulate a Christmas tree's post-harvest lifecycle, over 13 wk, from lot (outdoor) to home (indoor) to discarding (outdoor). Our results show that crawlers continue to emerge from post-harvest Fraser fir for up to 40 and 90 d in our seven- and 13-wk studies, respectively. Moreover, we found live females with eggs present for up to 50 d post-harvest. These findings highlight the potential risk of introducing this scale to new areas via Fraser fir Christmas tree shipments.