Increased incidence of oystershell scales in fruit orchards.
The biology of several oystershell scales (Diaspididae) which are related to Quadraspidiotus perniciosus, namely Q. pyri, Q. ostreaeformis and Q. marani is briefly described. These scales have recently been found to cause damage in fruit orchards in Switzerland. Notes are given on their morphology as an aid to identification of the different species. So far little is known about effective control measures.