- Author: Elizabeth E Grafton-Cardwell
The 2nd crawler emergence begins at 1650 degree days (above a 53oF threshold after the 1st male flight in early March). Kern and Tulare counties will be reaching that threshold next week. See my web site for details: http://ucanr.org/sites/KACCitrusEntomology/Home/California_Red_Scale/Degree_Days_885/
Pesticides like Movento that require 1-2 weeks for uptake should be applied now. Products that kill crawlers directly such as organophosphates and oils should be applied as soon as the peak of crawler activity has been completed. Use crawler tapes to define that point in time more clearly. Wrap double sticky tape around a branch near female scales and replace and examine it once a week to count the crawlers caught along the edge of the tape. This will telll you when the crawlers are actively emerging. Insect growth regulators such as Applaud and Esteem should be applied after the crawlers have finished emerging because contact with the scales is important and it these products are not going to kill the scales until they try to molt to the next instar.