104 F. W. DRY. _ 



(3) In experiments in the laboratory many hundreds of red scale larvae have 

 been placed on the leaves of coffee plants. Many of them secreted their 

 white covering, but none made any further progress. Larvae similarl}' 

 placed on citrus as controls lived and attained maturity and themselves 

 produced offspring. 



On the citrus plants, to which reference has been just made, the life-history of the 

 red scale was worked out, the larvae having been placed on the plants in the middle 

 of November 1917. The times when the various stages in the life-history were first 

 reached were as follows : — 



After the first day most of the larvae had secreted a covering. 



After eight days the " pimple " was visible in the centre of the scale. 



The first moult took place after 18 days. 



The second moult of the female took place after 50 days. 



The first male emerged on the 65th day. 



The first larvae of the next generation were observed after 110 days. 



The average daily temperatures during this life-cj'cle were : minimum, 54-5° F. ; 

 maximum, 805° F. 



Unfortunately the eradication of red scale has proved impracticable, but we ma}^ 

 hope that coffee is immune. 



Citrus is not at present an important crop in the country, though a great many 

 people have a small number of trees. At local prices fumigation is impracticable, 

 so that spraying is the control mea.sure recommended. 



The West Indian red scale, Selenaspidus articulatus, Morgan, has several times been 

 mistaken for the common red scale by citrus owners. It occurs on both citrus and 

 coffee, and has been found in widely separated parts of the country, but has not been 

 known to do serious harm ; often only a single individual will be found on one leaf. 

 In one citrus orchard in the Songhor district, a small number of trees could be described 

 as badly infested. The fruit was attacked as well as the leaves, hundreds of 

 individuals being found on a single orange, which was thus rendered quite unsightly. 



A citrus plant was infected in the laboratory, at the same time as those on which 

 the red scale life-history was worked out. Larvae of the next generation were first 

 observed after 120 days. 



