Codling moth (Cydia pomonella) is the major insect pest of pome fruit (apples and pears) in Montana.  This dataset reports codling moth damage to apple fruit ("strikes") in Montana orchards where site managers were not applying pesticides to control codling moth.  Data was collected in August or September of 2019 and 2020.  Certain sites east of the continental divide have nominally lower incidence of codling moth damage to fruit than sites west of the divide.  Due differences in weather year-to-year, we recommend continued monitoring.  

Montana orchards where codling moth was not managed were surveyed for damage to fruit in August and September of 2019 and 2020.  Damage to fruit was assessed by looking for exit holes left by codling moth larva. These exit holes are termed "strikes" and are approximately 3 to 5 mm in diameter, and often filled with frass (poop) to the point of overflowing (see pictures).  Personnel were instructed to count the number of strikes in up to twenty fruit per tree, trying to include fruit from all parts of the tree canopy.  Where possible, twenty trees per site were assessed, although some sites had fewer trees.  Tree variety was recorded, where known.  Many of the sites are "heritage" sites, or remnant orchards from the Montana apple boom around the early 1900s.  Trees at these sites tend to be large and assessing fruit from all parts of the canopy is not safe, especially for personnel working alone.  In addition, varieties are not always known.

This dataset is a reference for a MSU Extension Bulletin titled "Managing codling moth (Cydia pomonella) in Montana" (currently in draft, 10/9/2020).  Its purpose is to illustrate that codling moth is either not present or causes less damage at some orchard sites in Montana, as well as to provide access to raw data for personnel monitoring codling moth in the future.