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THE RED SCALE, ClIKYSOMPHALUS AURANTII. MASK., 

 IN KENYA COLONY. 



By F. W. Dry, M.Sc, 

 Kcxcnflv Assistant Government Entomologist, Kenya Colony. 



The first record of red scale in Kenya Colony in tlie lile of the Entomological 

 Laboratory is for 1914, on citrus. It is"^known that the scale has been brought into 

 the country in at least one consignment of citrus, which, being accompanied by a 

 certificate from the country of origin that the plants were free from insect pests, was 

 allowed to enter the country under the Plant Import Regulations then in force, without 

 being inspected. It seems, therefore, likely that red scale is not indigenous to the 

 country, but an introduced pest. 



In this belief, an attempt at eradication was made, in the hope that the insect might 

 be prevented from becoming established in the country, and the citrus crop thus 

 saved from a costly enemy. This attempt was also undertaken because of the possi- 

 bility that red scale might attack coffee, a very much more important crop in the 

 country than citrus. This was recognised as a danger for two reasons : first, because 

 red scale in other countries has a very wide range of food-plants ; and secondly, 

 because quite a number of .scales in 'Kenya Colony attack both citrus and coffee. 

 These are: Icerva purchasi. Mask., Saissctia hemisphaerica, Targ., Saissetia nigra, 

 Niet., Coccus hcsperidum, L., Ceroplastes ccriferns. And., and Selcnaspidns articiilatus, 

 Morgan. 



Accordingly, the importation of citrus into the country was prohibited. At the 

 same time, "owners of citrus attacked by red scale were advised to destroy such trees, 

 which were replaced free from the Government Farm, Kabete. Compulsory powers 

 were not sought, but whenever planters were asked to destroy infected trees under 

 this scheme, they consented to do so. 



Commencing in 1917, inspections of citrus orchards and nurseries in search of red 

 scale were made by the staff of the Division of Entomology and by the late Mr. J. J. 

 Adams. A circular letter was sent out to citrus owners, accompanied by a specimen 

 of red scale, asking them to make a search for the insect on their trees and to report 

 the result. Sometimes it was found that other insects, such as Coccus hesperidmn 

 or Selenaspidus articidatus, or the citrus Psyllid, Trioza sp., were mistaken for red 

 scale, so owners who reported the presence of this insect were asked to send a specimen 

 from their trees. 



By these means it was found that red scale was widely distributed in the country 

 and that large numbers of trees were attacked. In some cases, citrus not being a 

 profitable crop, little care has been taken of the trees and the scale has been allowed 

 to multiply unchecked, so that in some neglected orchards great damage has been 

 done by it. 



In addition to citrus the plants now known to be hosts of red scale in this 

 country are roses, apple, plum and sisal. 



Fortunately, the fears that red scale might attack coftee have not so far been 

 reahsed, and the following evidence, obtained both in the field and in the laboratory, 

 is encouraging : — 



(1) Red scale has never been observed or reported on coffee. 



(2) A field of coffee, adjacent to some citrus trees, very badly infested with red 



scale, has been kept under observation. The citrus is very close to the 

 outside row of coffee, the branches of the two often being in contact. All 

 that has been found on the coffee, are objects that appeared to be red 

 scale larvae, which have secreted the white covering just after settling 

 (this the larvae have also done when put on coffee in the laboratory) and 

 older individuals that were dead and had in all probability been washed 

 off the citrus on to the coffee. 



