Diaspis. 89 



Habitat. — I have found this species on many different plants in Ceylon, 

 viz., Callicarpa lanata, Tylophora asihmatica, heliotrope, peach, and several 

 unidentified trees, but it is chiefly noticeable upon cultivated geraniums in 

 gardens, where it is really a most serious pest, the insects being frequently 

 massed upon the stems to such an extent as to kill the plant. The presence 

 of the pest can scarcely escape notice, the stems appearing to be thickly 

 encrusted with a white scurfy matter, which proves to be composed of masses 

 of the male scales. The female scales are much less conspicuous. I find this 

 species at all times of the year, but I think its ravages are worse in the early 

 (dry) months — January, February, and March. Plants that are sheltered from 

 the weather are more particularly subject to attack. This insect is found in 

 widely separate quarters of the globe. It was originally noted by Professor 

 Tryon on peach trees in Australia, and described by him under the name of 

 Diaspis amygdali. It subsequently attracted attention in the United States of 

 America, where it attacks a large number of plants, but is especially injurious to 

 peach and plum trees. It was there identified as Diaspis lanattis (Morgan and 

 Cockerell) ; but, as pointed out by Mr. W. M. Maskell {Trafis. N. Z. Instit.^ 

 1894, p. 44), the American insect is in all specific points identical with the D. 

 atnygdali, previously described by Professor Tryon. I have myself compared 

 typical specimens from both countries, and can find no good points of dis- 

 tinction. Professor Cockerell records this pest as occurring in Jamaica on 

 grape, peach, cotton, capsicum, and a variety of other plants too numerous to 

 mention. It is said to affect the ' Papaw ' tree {Carica papiya) in the island of 

 Trinidad. I possess specimens collected by Mr. Albert Koebele in Fiji ; and, 

 more recently, what appears to be the same insect has brought itself into notice 

 as an injurious pest on mulberry trees in Japan, where it has been studied by 

 Professor C. Sasaki of the Agricultural College, Tokyo, and again redescribed 

 under the name of Diaspis patelliformis. Professor Sasaki states that in Japan 

 the insect breeds only twice in the year. 



Its wide distribution and the great variety of plants upon which this insect 

 is able to thrive constitute it a dangerous pest, and it has been fully recognised 

 as such in America, where great efforts are being made to eradicate it. We 

 may consider ourselves fortunate in Ceylon that the insect has chosen such an 

 unimportant plant as the geranium for its head-quarters. It would be desirable, 

 if possible, to exterminate it before it has acquired a more expensive taste. If 

 it were restricted to geranium plants, this would be comparatively easy, by the 

 destruction of all affected plants ; but, unfortunately, it has firmly established 

 itself upon a common indigenous shrub — a plant with woolly stems and leaves 

 {(Callicarpa lanata) — which is too plentiful and widely distributed for any such 

 wholesale measures. From experiments conducted by the U. S. Government 

 entomologist it appears that the scale of this insect is able to resist some of 

 the strongest insecticides ; in fact, nothing but pure kerosene emulsion seems 

 to have been really fatal ; but, in the case of growing plants, this remedy would 

 be as injurious as the disease, and would prove as fatal to the plants as the 

 parasites. More dilute washes (one of emulsion to nine of water) have proved 

 efficacious at the time the newly hatched larvae are on the move. 



I have bred from this insect a minute hymenopterous parasite, which has 

 been identified by Prof. Howard as Aspidiophagus citrinus (Craw.) 



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