Eleventh Keport of the State Entomologisti 201 



reproduction of their young. The male, however, undergoes a complete 

 transformation and becomes winged, but with only a single pair of wings 

 of very simple structure (see in Figures 3, 2, and 3 in Plates VIII, IX, 

 and XIV. It lives but a day or two, dying speedily after the fulfillment 

 of the purpose of its being. It takes no food, for in this stage it pos- 

 sesses no mouth or digestive organs. 



Some Species Useful. 

 A few species of the Coccidae are of service to us, such as the Coccus 

 cacti from which the valuable dye, cochineal, is obtained ; the Carteria 

 lacca which excretes the material known to us as shellac ; from another 

 species we have the commercial article known as china wax; and still 

 another species occurring in Arabia produces a solidified honey-dew 

 called " manna," which " is thought by some to have been the heaven- 

 sent manna that nourished the Hebrews in their wanderings." 



Number of Species. 

 About 125 species of North American Coccidae have been described, 

 and others are being brought to notice each year, either from having 

 been previously overlooked, or recently introduced from abroad. All of 

 them are destructive in proportion to their rapidity of multiplication and 

 the greater or less economic importance of the plants that they infest. 



Before proceeding to the consideration of the San Jose scale, — the sub- 

 ject of this bulletin, it may be of service to refer briefly to a few other 

 species which, although common in the State of New York, and quite 

 harmful to the trees that they infest, are still almost wholly unknown to 

 the fruit-grower and to others who are suffering from their presence. 

 From the figures given of them, they may at once be distinguished from 



the San Jose scale. 



The Apple-tree Bark-louse. 



The most common of these is the apple-tree bark-louse, shown in Fig. 

 I of Plate VIII, in its natural size as it occurs on the bark ot trunks and 

 limbs, often more abundantly than is represented in the cut, completely 

 covering the bark and overlaying one another, and lending an increased 

 diameter to the infested twig. The color of the scale is brown or ash- 

 gray, nearly approaching that of the bark. The female scale measures 

 about one-twelfth of an inch in length, of a long, usually more or less 

 •curved form, pointed at one end on which a magnifier may show the 

 yellowish cast-off skin of the insect, and rounded at the other end. From 

 its peculiar shape it has been frequently written of under the name of the 

 oyster-shell bark-louse. It bears the scientific name oi Mytilaspis pomorum 



