However, even oil has a negative impact on Aphytis because it can synchronize the scale stages and leave the Aphytis without 3 rd instar scale to lay their eggs in. Citricola scale is very sensitive to that broad spectrum insecticides, Lorsban, Supracide, and Sevin that we used for California red scale for many years. We stopped using those insecticides for California red scale in 1997 because many populations of red scale were resistant to them. In 1998 and 1999 many growers used Esteem to control red scale and it did a great job on that pest. Esteem does not work very well on citricola scale.
Esteem affects molting and citricola scale only molts twice per year.
Here we are 3 years later, and we haven't used the Lorsban, Supracide, or Sevin treatments in many orchards for 2-3 years. Citricola scale is popping up it's ugly head in quite a few orchards throughout the San Joaquin Valley. Be on the lookout for the gray bodies of citricola scale lining up on the twigs. They will mature into females soon and begin releasing crawlers onto the leaves in May-July. If you have citricola scale in your orchard, Esteem will not help you and you need to go back to a Lorsban, Supracide, or Sevin treatment for scale control.