82 INSECTS AFFECTING THE ORANGE. 



they destroy great numbers of the young lice, as soon as the latter have 

 fastened themselves to the bark, and while their scales are still soft and 

 thin. They also creep into the open end of scales which have begun to 

 hatch, and destroy a portion of the eggs. The scales vacated by para- 

 sites, in which have been left convenient open doorways, furnish the 

 Mites with secure retreats and places of deposit for their eggs. Usually 

 the dry and distended skin of the Coccid is left by the parasite, nearly 

 filling the scale, and with a minute exit hole. immediately opposite that, 

 in the outer shell. Thus the Mites or their young and eggs are provided 

 with a double envelope separated by layers of confined air, and nearly 

 impervious to liquids. It is, therefore, not astonishing that applica- 

 tions sufficiently penetrating to kill Scale-insects do not reach the Mites 

 and their eggs thus protected. In fact the latter very frequently in- 

 crease enormously after an effective application, because the loosening 

 of the scales by the wash enables them to penetrate to and feed upon 

 the dead or dying Bark-lice, and the supply of food is for a time largely 

 increased. 



To cause a marked increase in the number of the Mites, it is some- 

 times sufficient to loosen the scales here and there upon the trunk and 

 branches which are most thickly encrusted with them, by scraping the 

 bark with a stick or knife blade. This gives the Mites an increased sup- 

 ply of food, and stimulates them to active breeding. The result is 

 often to effectively check the progress of the Scale-insects for the time 

 being, although they cannot be exterminated in this way. The method 

 is not advanced as a practicable remedy, and cannot be made to replace 

 the proper application of insecticides, but from its simplicity it is fre- 

 quently useful as a means of gaining time, when remedies are not at 

 hand. 



GLOVER'S ORANGE MITE (Tyroylyphus f glorerii Ashniead). [Plate 

 VI, Fig. 5.] This is the commonest species found among Orange Scale- 

 insects; it is also the smallest species and the most active and rapid in 

 its movements; it is somewhat longer than broad, slightly flattened ; 

 in color it varies from pure white to yellowish, and often a pale pink or 

 . flesh-color. This color- variation is due to the varying nature of its in 

 testiual contents, seen through the semi transparent body. Length 

 about O.l mm ( - ro Vo- inch).* 



The eggs are white, and are deposited either singly or in small groups, 

 under a tangle of spider's web, among dead scales, &c. ; lurking places 

 in which the white, six legged young congregate and undergo their trans- 

 formations. 



* The form iu most soft-bodied Acariuais very changeable., depending upon the con- 

 dition of the animal, whether full-fed, or depleted by fasting. The figure of this 

 species on Plate VI represents the shape commonly seen. When emaciated, the sides 

 of the body become deeply sinuate or lobed, deep pits are formed upon the upper sur- 

 face in front, and several transverse folds iu the skin appear to divide the abdominal 

 portion into segments. In plethoric individuals, the disteution of the body into an 

 oval sack obliterates every trace of fold or depression upon its surface. 



