California Red Scale Degree Days
California Red Scale Degree Days
2023 CRS degree day updates.
| County | DD as of Aug 16, 2023 | Next life event CRS |
| Kern | 2761 | 4th gen flight. |
| Tulare | 2575 | Third gen. crawlers happening, next 4th gen flight. |
| Fresno | 2624 | Third gen. crawler happening, next 4th generation flight. |
| Madera | 2355 | Third generation crawlers. 4th generation flights in 2-3 weeks. |
Pheromone traps are used to monitor California red scale (CRS) male flight activity. Following the biofix (first male flight) degree days (DD) are used to predict when the crawler emergence or when next generation flight takes place. Degree days for CRS are heat units accumulated above the lower developmental threshold (LDT) of CRS.
LDT for California red scale = 53 F
Degree days from Biofix to crawler emergence = 550 DD
Degree days for the second generation flight = 1100 DD
Degree Days for the second generation crawler = 1650 DD
Degree days for the 3rd generation flight = 2200 DD
Degree days for the third generation crawler = 2750 DD.
Higher average daily temperatures mean faster accumulation of degree days, hence faster development of insects.
This page updates current degree days for Kern, Tulare, Fresno, and Madera counties.
Low daily average temperatures in California during early spring has delayed CRS season in the valley. Bioxfix in all counties came ~4 weeks later (Biofix in earlier years has been March 1st week). Click here for an article.
California red scale pest memos for 2023 season