COCCIDM 



131 



control them by proper laws for exclusion. In determina- 

 tion, the appearance and color of the scale and the appear- 

 ance it gives to the trees are very important. There are 

 several subfamilies but the following include the x\merican 

 species of importance. 



The Dactylopiincp, including the mealy bugs and related 

 forms, differs from other members of the family largely in 

 the fact that the species are less fixed in habit. The mealy 



Fig. 86. — Orlhczia aolidaginis Sanders on goldenrod leaves, 

 author.) 



(Photo by 



bugs are particularly active and capable of traveling about 

 readily. They are covered with a whitish, mealy secretion 

 .from which they derive their name, and in temperate regions 

 are found for the most part in greenhouses but there are a 

 few native outdoor species. The common mealy bug of 

 greenhouses (Pseiulococcvs citri) is a very well-known pest 

 and may be found in different stages of its life history in 

 almost any greenhouse and frequently upon house plants 

 if kept where there is moisture. Fumigation and the use of 

 washes are available for their control. 



