DlPTERA. 



Two or three species of true flies have been found to be parasitic on scale-insects ; but no instance 

 of this sort has been observed in Jamaica. I have, indeed, bred numbers of a new species of Cecid 

 fly (Diplosis coccidarum n. sp.) from scale-insects found in Kingston, but I believe that this breeds 

 merely in the secretions and old skins of the Coccids, being thus a guest or inquiline, rather than a 

 parasite. 



Hemiptera. 



A few species of true plant- bugs are known to prey upon Coccidae. 



Arachnida. 



Some species of mites have been found to destroy Coccids. In Jamaica, small mites are frequently 

 found associated with scale-insects, but I have not ascertained that they do them any injury.* 



How COCCID^E ARE SPREAD BY HUMAN MEANS. 



The injuries due to Coccidse have probably been much more than doubled by the way they have 

 been carried from one country to another on plants. It is a well-known fact that many species of 

 animals and plants thrive more in foreign countries than in their native land : and the reason of this 

 is, that they are, through the change of locality, removed from most of their natural enemies and com- 

 petitors. The fluted scale, Icerya purchasi, is a well-known example. When introduced into California 

 from Australia, it multiplied enormously, and became a far more serious pest than it had been con- 

 sidered in its native country. It was, indeed, attacked in its new home by a few insects, but they were 

 quite insufficient to keep it in check. Mr. Koebele went to Australia to look for the natural enemies 

 of the fluted scale, and found the scale itself quite rare there, being attacked by very important 

 enemies, some of which he brought alive to California. These were liberated in the infested districts, 

 and one especially, the lady-bird Vedalia cardinalis, proved extremely effective, so that the Icerya- pest 

 was speedily reduced, and the despair of the fruit-growers gave way to hope as the equilibrium of 

 nature began to be restored. 



Mr. R. Allan "Wight has written a graphic account of the Icerya and Vedalia in an Australian 

 paper, the "Garden and Field," which has lately been reproduced in "Insect Life." In New 

 Zealand the Icerya is sometimes a great pest, and Mr. Wight gives the following description of the 

 way it is cleared off by the beetle ; — 



" Some two years ago everything seemed white around Auckland with the clustering Icerya, a 

 great many orange and lemon trees (including one entire lemon orchard), were dead, and the prospect 

 was as gloomy as could be, till Vedalia (whioh had been accidentally imported from Australia) 

 appeared on the scene. Astonishing as it may eeem to be, and incredible, within one year hardly 

 any of the scales were left, and the lady-birds had also disappeared. The little beetles are rank can- 

 nibals when pressed by hunger, and as no one was able to discover any other food but Icerya upon 

 which they will feed, it was feared that, in the absence of Icerya, they would become extinct." 



If scale-insects, when taken to new countries, were only as injurious as in their native homes, 

 there would be strong enough reasons for not importing them ; but when we see that being 

 freed from their enemies, they may increase to a much greater extent, the necessity for preventing 

 their introduction becomes a very pressing one. The ease with which scale insects may be carried 

 from one part of the world to another is well known. Some of the most interesting scales described 

 in late years have been found on foreign plants in hot-houses in England, where they must have been 

 carried from the tropics. In the West Indies, we have two mango scales, the Vinsonia and Lecanium 

 mangiferm, which doubtless reached us on plants from the East Indies ; while quite recently, a New 

 Zealand species, Chio?iaspis minor of Maskell, has been found commonly in Kingston. Various species 

 of European origin have spread widely in the United States, and while some of them, as the black 

 scale (Bernardia olece), are now abundant in Jamaica, there are others which do not seem to have 

 reached this Island, — and it may be hoped, will never be allowed to do so. 



One of the destructive scales found in other West Indian islands, and in the United States, but 

 not apparently as yet in Jamaica, is Chionaspis citri, which affects the orange. The following account 

 of its introduction into Bermuda is from a report by U. S. Yice Consul J. B. Heyl, of that island : — 



"This island was clear of insect pests until sometime in 1858 or 1859, when a vessel was brought 

 here in distress, with a cargo of oranges, which were sold at auction, and the fruit was carried all over 

 the island, and in a few months our flourishing trees were covered with an insect which gave the trees 

 the appearance of being whitewashed. This insect fed on the bark of the tree, extracting the yellow 

 sap therefrom and causing the bark to curl up. Every device thought of was tried, but the island 

 was soon cleared of nearly every tree. All this came from the distress cargo." 



When we import a useful plant from another country, it is almost sure to be attacked by some of 

 our own insects, and if at the same time we import its natural enemies, and these increase 

 abnormally as desoribed above, it is easy to see that we are placed in a position of great disadvantage, 

 so much so, that even though soil and climate are favourable, we cannot hope to cultivate the new 

 plant so successfully as it was cultivated in its own country. 



But, on the other hand, if we introduce any plant and exclude its natural enemies, it will almost 

 certainly not be attacked so severely here as it was where it came from, and we are in consequence, 

 placed in a more favourable position for cultivating it (always assuming a suitable soil and climate) 

 than those who raised it in its native country. The more the plant in question differs from any of our 

 native plants, the more is this likely to be the case, because there are less likely to be insects here ready 

 to attack it. 



* Certain fungi are found on dead scale insects ; such ae Microcera coccophila, Mont ; found by the writer associated 

 •with Aspidiofou articulatus on Citrus at Moneague. 



