Woglum, R.S. 1946 Unusual scale development and use of DDT complicate summer control programs in central California.. The Exchange: Pest Control Circular No. 140: 1-2.

Notes: Coccus pseudomagnoliarum, citricola scale, was observed during the summer to spread from leaves to stems for the first time. With the failure of sulfur and lime controls, DDT has begun to be used experimentally. Cottony cushion scale (Icerya purchasi) also shows a tendency to increase, particularly in DDT treated groves. Mention is also made of purple scale control.