450 ANIMALS INTRODUCED UNAWARES 



THE APPLE SCALE 



The Mussel or Apple Scale (Leptdosaphes ulmi or 

 Mytilaspis pomoruni] (Fig. 76, p. 449), a tiny Hemipterous 

 Insect or Plant-bug, is supposed to have belonged originally 

 to the Old World, but wherever the apple has gone the 

 Mussel Scale has kept it close company, travelling most 

 frequently perhaps on the stems of transported apple-trees, 

 but sometimes on the apples themselves. It is common in 

 Britain, common indeed throughout Europe, northern and 

 southern Africa have it, and it has reached far Japan ; in 

 the New World, Canada and the United States have 

 publicly declared it a pest, and strive to intercept new 

 arrivals, and Chili is concerned about its ravages ; across 

 the seas, Australia and New Zealand 'have been forced to 

 make efforts to control it within their boundaries. 



MEDITERRANEAN FRUIT FLY 



It is the habit of another series of animals to conceal 

 themselves, still more effectively, within the apples which 

 are to scatter them abroad. Of such none offers a better 

 illustration than the Mediterranean Fruit Fly (Ceratitis 

 capitata), a notorious pest of many fruits. The female of the 

 Fruit Fly, a small two-winged fly with spotted yellowish- 

 brown body and yellow wings, pierces the apple skin and 

 lays a few eggs in each puncture. In from two days to over 

 a week, according to the warmth or coolness of the weather, 

 the larvae hatch from the eggs and feed upon the pulp of the 

 apple for from one to three weeks, when they are full-fed 

 and emerge from the fruit, ready for pupation. In a like 

 period, the adult fly emerges from the pupa case and in 

 from five to ten days thereafter is ready to commence the 

 egg-laying which is to found a new generation. Now it is 

 evident that this life-history and the impartiality with which 

 the Fly attacks many kinds of fruit, afford much opportunity 

 for the unnoticed dispersal of the Fruit Fly ; for fruit in 

 which the eggs have been placed in one continent may set 

 free its cargoes of full-fed larvae in another. It is not 

 surprising to find, therefore, that while the original home 

 of the so-called Mediterranean Fruit Fly appears to be in 

 the West Indies, the pest has established itself, thanks to 



