Phenology models predict timing of events in an organism's development. For many organisms which cannot internally regulate their own temperature, development is dependent on temperatures to which they are exposed in the environment.
Information in this database comes from published articles. It may be used in conjunction with field monitoring and a degree-day calculator.
Note: Before using a model that was not field tested in your location, you should test the model for one or more seasons under your conditions to verify that it will work for you.
Model 1
Yu, D. S., and R. F. Luck. 1988. Temperature-dependent size and development of California red scale (Homoptera: Diaspididae) and its effect on host availability for the ectoparasitoid, Aphytis melinus DeBach (Hymenoptera: Aphelinidae). Environ. Entomol. 17: 154-161.
- Location of study: Riverside, California (laboratory & field studies)
- Lower developmental threshold: 52.7°F (11.5°C)
- Upper developmental threshold: 86.0°F (30.0°C)
- Method of calculation: Hourly (UC IPM recommends Single Sine)
- Cutoff method: not specified (UC IPM recommends Horizontal)
Degree-day accumulations required for each stage of development
Females scale on Lemons:
- 1st instar: 190.6 (°F) 105.9 (°C)
- 1st molt: 126.2 (°F) 70.1 (°C)
- 2nd instar: 134.5 (°F) 74.7 (°C)
- 2nd molt: 159.8 (°F) 88.8 (°C)
- 3rd instar: 173.9 (°F) 96.6 (°C)
- Pre-crawler interval: 360.4 (°F) 200.2 (°C)
- Generation time(crawler to crawler): 1145.5 (°F) 636.4 (°C)
Model 2
Bimboni, H. G. 1970. The relation of variation in temperature to the rate of development of immature stages of California red scale, Aonidiella aurantii (Maskell), on citrus. Masters thesis, Department of Entomology, University of California, Riverside.
- Location of study: Riverside, California (laboratory studies)
- Lower developmental threshold: 53.0°F (11.7°C)
- Method of calculation: Max-min (UC IPM recommends Single Sine)
Degree-day accumulations required for each stage of development
Females scale on Grapefruit:
- Generation time (crawler to crawler): 1199.0 (°F) 666.1 (°C)
Model 3
Grout, T. G., W. J. DuToit, J. H. Hofmeyr, and G. I. Richards. 1989. California red scale (Homoptera: Diaspididae) phenology on citrus in South Africa. J. Econ. Entomol. 82: 793-798.
- Location of study: South Africa (field studies)
- Lower developmental threshold: 53.0°F (11.7°C)
- Upper developmental threshold: 100.0°F (37.8°C)
- Method of calculation: Double sine
- Cutoff method: Horizontal
Degree-day accumulations required for each stage of development
Host: Lemons
- Generation time (adult to adult): 896.8 (°F) 498.2 (°C)
Host: Oranges
- Generation time (adult to adult): 1038.2 (°F) 576.8 (°C)
Host: Grapefruit
- Generation time (adult to adult): 1097.3 (°F) 609.6 (°C)
