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XII. On the economic importance of the parasites of Coccidse. 

 By Alice L. Embleton, B.Sc, 1851 Exhibition 

 Science Research Scholar. Communicated by Dr. 

 David Sharp, M.A., F.R.S., etc. 



[Read April 16th, 1902.] 



Of the numerous families of insects which possess great 

 economic importance, it is generally admitted that there 

 are none more deserving of attention than the Coccidx — 

 insects popularly known as " mealy bugs," " scales," and 

 "bark lice." The enormous damage they do to plants of 

 various kinds in all climates is effected by means of the long 

 thread-like proboscis which is buried deeply in the host's 

 tissue, and through which the sap is sucked.* They are 

 excessively prolific, and their insignificant size, too, enables 

 them only too easily to escape detection, the result being 

 that many of them are becoming almost universally dis- 

 tributed. Add to this the fact that they are notoriously 

 difficult to kill, and it is then easily comprehended that 

 they are amongst the worst insect-pests the horticulturist 

 has to reckon with. Not only are there immense numbers 

 of individuals in a species, but also there are a great many 

 species — the number already known has recently been 

 computed at over a thousand. f 



In spite of their undeniable importance as pests of a well- 

 nigh ubiquitous character, they have received compara- 

 tively slight attention, with the result that the study of 

 these creatures is but little advanced, being far in arrear of 

 the state of knowledge in several other departments of 

 Entomology. In this country in particular, the study of 

 Coccidc'B has been carried on by one or two naturalists ; in 

 America, especially during recent years, considerable inter- 

 est has been taken in them and their economic aspects, 

 for in that country it has been necessary to combat the 



* KocHS [Jahrb. Hamb. Anst., xvii, 1900, Beiheft iii.] has recently 

 studied the subject of the penetration of this proboscis into the plant 

 tissues, and the effect its presence has on the host. 



f "A check -list of the Coccidai." T. D. A. Cockerell. Bull. 

 Illinois Lab., iv, pp. 318-339. 



TRANS, ENT. SOC. LOND. 1902. — PART II. (JUNE) 



