This is in response to a question on the bcfruits discussion group about Codling Moth Biofix. The following information is intended to clarify biofix, if I further complicate things please let me know. Codling Moth is one of the most studied and best understood fruit tree insects. There is a lot of information on the web, unfortunately not all of it is correct. The biofix approach to predicting Codling Moth development has been used for more than 40 years, there have been some recent refinements.
The initial use of this information was to time applications of insecticide sprays. Codling Moth Traps are a monitoring tool to detect the presence of adult moths. These traps are baited with female sex pheromone so only capture males. Codling Moth development can be tracked using degree day (DD) calculations with a 10 °C base. Prior to the development of the no-biofix method, Codling Moth life stages were tracked/predicted (and still are by many orchardists) using a Biofix. The Codling Moth Biofix is when the first moth emerged from the overwintered stage is trapped. Overwintering moth emergence will last for about 6 weeks after the first trap capture. At biofix, the degree day calculations for the year are reset to 111 accumulated DD (this is a historic number, current models including the Okanagan SIR Program are using 100). The current model predicts that first brood egg laying starts at 150 DD and first brood egg hatch starts at 220 DD. You also need to include the fact that mating and egg laying occurs when twilight temperatures are above 15 °C. See these web sites for more DD information oksir and WSU.
If you plan to apply a spray to control codling moth (either conventional insecticides or organic insecticides) the timing will be sometime (timing recommendations vary) after egg hatch as the target is the newly hatched larva. If you are a gardener and plan to use barriers such as apple sox to prevent the moths laying eggs on your fruit, the sox must be on the fruit before egg laying. If you are a commercial orchardist using Surround you need to apply it before egg laying starts. If you are a commercial orchardist using mating disruption the pheromone dispensers must be in the orchard before mating starts.
Using a biofix provides better synchronization between the insect’s development and degree-day accumulations, so it is a more exact way to predict Codling Moth life stages, such as egg hatch. The question is, do you need that much precision.
The no biofix approach does not use Codling Moth traps. It uses the accumulated DD from January 1st of each year. A detailed table of this information is here: NoBiofix
The BC based Farmwest web site has an online live calculator that will determine Codling Moth DD from any date you chose for a large number of locations across BC. Farmwest Pest