498 CITRUS FRUITS AND THEIR CULTURE. 



II. ARMORED SCALES. 



The Purple Scale, (Mytilaspis oitricola Packard). 

 This is one of the commonest and most conspicuous citrus 

 scales in Florida. The insect seems to be widely known 

 wherever the orange is grown, either in this country or 

 abroad. Hubbard observed in 1885 that it was more 

 abundant in the northern than in the southern portions 

 of the orange belt. The freezes since that time seem to 

 have reversed this order of distribution. 



The scale of this species is one of the largest in the 

 genus. The scale of mature females sometimes reaches 

 a length of 0.12 of an inch (3 mm.), and that of the 

 male 0.05 of an inch (1.4 mm.). The name, "Oyster 

 Shell Bark-louse," has been applied to one member of 

 the genus, Mytilaspis pomorum, a common apple pest, 

 because the general outline of the scale, together with 

 its ridgings and markings, are so suggestive of an oyster 

 shell in miniature; the purple scale, Mytilaspis citricola, 

 and in lesser degree, the long scale, Mytilaspis gloverii, 

 share this resemblance, and so it is not uncommon to hear 

 the term, "Oyster Shell Bark-louse," applied to any one 

 of them by the general public. The form may be de- 

 scribed as broadly trumpet-shaped, increasing in width 

 behind, often curved like an oyster shell, but rarely or 

 never with the sides parallel. The surface is glossy and 

 smooth and from a light to a dark red-brown purple 

 color. The male scales, being less than half the length of 

 the females, of a more linear shape and straight outline, 

 may suggest some other species of insect upon superfi- 

 cial examination, but its identity cannot be confused with 

 any other species than the long scale, Mytilaspis gloverii, 

 the female of which is twice as long as the male citricola. 

 and the male of which is shorter and rather more slender. 



