HEMIPTERA: THE TRUE BUGS 



83 



are found so frequently upon the bark of trees. If you 

 examine the twigs or leafy branches of some apple trees, 

 you will probably find what look like miniature oyster 

 shells upon the bark. These are ex- 

 amples of the Oyster-shell Scale. If > 

 you will carefully pry up one of these 

 tiny scales and look at its under side 

 with a lens, you will probably find a 

 large number of minute oval eggs. 

 Early in summer, these eggs hatch into 

 tiny insects that wander over the sur- 

 face of the young bark. In a day or 

 two, they fix themselves in one place 

 by inserting their beaks into the tissues 

 and sucking out the sap, where they re- 

 main and gradually develop their scaly 

 covering. 



One of the most destructive insects 

 ever introduced into America belongs 

 to this family. It is the notorious San 

 Jose Scale, a pest that during recent 

 years has attracted more attention from 

 fruit growers than any other insect. 

 It is especially dangerous because its presence is difficult 

 to detect until it becomes sufficiently abundant to injure or 

 kill the infested tree. It then appears as a curious scaly 

 crust on the bark. When only a few are present, they are 

 difficult to find, as they are simply small circular spots of 

 much the same color as the bark, plainly seen only through 

 a magnifying glass. 



The appearance of the individual scales is well shown 

 in the pictures on the next page. Each scale is a 

 small circular object, closely attached to the bark, not more 



Scale Insects on 

 Rose 



