170 Insect Pests. 



Some scale insects have the male still rarer, and in others no 

 males whatever have been found. 



The little active larva? appear to be able to wander some distance, 

 and that they do so we know by the fact that we frequently find this 

 mussel scale on the apples and leaves. They are also carried about 

 by various natural agencies, such as the wind, birds, and by other 

 insects. In has been noticed that Ladybird Beetles carry them on 

 their backs from tree to tree. 



XATURAL ENEMIES. 



Like the Aphis, the Scale Insect has several natural enemies. 

 Ladybirds (CoccincUidcc) and their larva? or " niggers " devour them, 

 but not to any great extent in our country. Small hymenopterous 

 insects called Chalcid Flies (Chalcididce) lay their eggs in them and 

 so destroy them. "\Ve are sure to notice many of the mussel scales 

 on the apple trees with minute round holes in them. These are the 

 exit holes of the parasites, very similar to what we observe in the 

 aphides. The Blue Tit (Parus ccerulcus) and other birds pick the 

 scales off very ravenously, and often destroy large colonies of them. 

 Yet, with all these natural enemies, we get the Mussel Scale often 

 causing a great deal of damage in our orchards, especially when they 

 attack young and tender trees. These natural enemies evidently 

 cannot be relied on to do any appreciable good. 



ARTIFICIAL MEANS OF DISTRIBUTION. 



This scale is distributed artificially, namely, on nursery stock and 

 on fruit. In this way it has become a world-wide species. On 

 nursery stock it is not easy to detect, if present in very small numbers, 

 as the scales so closely resemble the colour of the bark. At the time 

 that stock is lifted for removal the scale insects are in the egg stage. 



Fruit also undoubtedly is another way in which it has been 

 carried from country to country ; the peel may get thrown about in 

 manure and rubbish heaps in gardens, and then the young larva? may 

 easily be carried by birds, etc., to the trees. 



Thirdly, they undoubtedly come over sea and distances by land 

 on other plants than fruit trees. 



GEOGRAPHICAL DISTRIBUTION. 



Europe generally, Algeria, Egypt, South Africa, Canada, L'nited 

 States, Brazil, Hawaiian Islands, Japan, Xew Zealand and Australia. 



