OF WASHINGTON. 319 



ON THE DISTRIBUTION OF CERTAIN SPECIES OF 

 MYTILASPIS. 



By H. G. HUBBARD. 



(Author's abstract. ] 



Mr. Hubbard spoke of the unreliability of tradition and early 

 records as a source of exact knowledge concerning the introduc 

 tion and spread from one country to another of pests like Scale 

 Insects, which are so easily transported upon living plants and 

 so difficult of specific identification even by expert observers. 

 He said that the published accounts of the introduction into 

 Florida of the two common orange scale insects, Mytilaspis 

 glover i and Mytilaspis citricola, were apparently exact and 

 circumstantial, 1 the Long Scale having, it is said, been brought to 

 Mandarin in 1838, by Mr. Robinson, on two small mandarin trees 

 which were obtained in New York from a ship which came from 

 China ; and the Purple Scale, according to Glover's account, 

 brought into the State some years later upon lemons imported 

 from Bermuda. 



Notwithstanding these very positive statements, which have 

 passed unchallenged into our literature, it is almost certain that 

 both are erroneous. The insects mentioned by Glover as coming 

 from Bermuda are clearly not Mytilaspis Scales ; and the Purple 

 Scale, to which his record has been supposed to refer had at the 

 time of which he wrote not yet reached Europe from the East. 

 It was not until the middle of the present century had been 

 reached and passed that it continued its westerly course and 

 spread over the islands of the Atlantic and the Carribean Sea, 

 attaining the continent of North America not much before the 

 year 1880. 



As to the Long Scale (M. glover i}, the fact that it is to-day 

 the principal pest of the orange in the interior of Mexico renders 

 the tradition of its introduction upon the North American con 

 tinent in 1838 altogether improbable. It is probable that this 

 scale was intoduced with the orange into Florida and Mexico by 

 the Spaniards at the end of the i6th or beginning of the iyth 

 century. Its irruption in 1838 was in fact but a continuation 

 of an epidemic of coccid pests of the orange which is known to 

 have overwhelmed the citrus plantations of Europe and the 

 Mediterranean in the early part of the century and to have spread 

 westward somewhat later, to the Azores, the Canaries, and finally 

 to Bermuda. 



In these days of rapid transit, which facilitates the interchange 

 of living plants between the most distant countries, insects of 



