ENTOMOLOGY 115 



like skin, the lower surface of the body gradually contracting until 

 there is nothing left but the shell, covering a mass of hundreds of 

 eggs. The eggs will hatch in a comparatively short time, but, as the 

 females come to maturity at different dates, the young from this spe- 

 cies are constantly appearing and spreading over the infested plants 

 between June and the end of October. The growth, however, is very 

 slow, and even those earliest hatched do not reach maturity until late 

 in autumn, the latest maturing in June and July of the following 

 year. 



While retaining the power of movement practically throughout 

 its development, this scale insect is very little apt to change its posi- 

 tion after it is once settled, or, at least, after it is half grown. There 

 is a general migration from leaf to twig, but the scale often develops 

 on the leaf if the latter remains vigorous and supplies it sufficient 

 nourishment. The remedial measures for the black scale are spray- 

 ing with the oily emulsions and the gas treatment. 



The Soft Scale. This scale insect also known as the turtle-back 

 scale or brown scale, is closely related to the black scale, but is a 

 much softer and more delicate insect. It changes in color with age 

 from a transparent yellow in the young to deepening shades of brown 

 in the adult. The adult scale has a length of 3 or 4 millimeters, is 

 turtle-shaped, and very much swollen, the body of the mother in the 

 last stages becoming a mere cap filled with young. In the early 

 stages the insect is thin and flat and semitransparent, so that it is 

 scarcely noticeable on the surface of the leaf or twig. It is very com- 

 monly found on various greenhouse plants, and has been carried to 

 all parts of the world on such material. In climates suitable for the 

 growth of the orange and lemon it occasionally gains a foothold on 

 outdoor plants. It has a gregarious habit, and commonly lives in 

 colonies, frequently covering the young limbs and the midribs of the 

 leaves. These colonies are usually not of long duration, being soon 

 attacked and exterminated by parasitic and predaceous enemies, the 

 soft texture of the insect not furnishing much, if any, protection. 

 The transformation and habits are very similar to those of the black 

 scale. It, however, is much more rapid in growth, and, where the 

 climate is favorable, goes through a continuous series of generations, 

 or broods, throughout the season. It readily yields to oily \vashes or 

 to the gas treatment. 



The Hemispherical Scale. This scale is also distinctively a 

 greenhouse pest, and it can hardly be considered as especially inju- 

 rious to citrus trees in orchards. It occurs all over the world, and oc- 

 casionally will multiply to a slight extent on orchard trees. The in- 

 dividuals are about the same size as those of the last two species. In 

 color it ranges from light brown in the young to dark brown, chang- 

 ing to reddish in the old scale. The adult scale is hemispherical in 

 shape, perfectly smooth and shiny, and this, with its color, readily 

 distinguishes it from the other two species. The remedies arc those 

 used against the black scale. 



The Florida Wax Scale. This very curious and striking scalo 

 insect secretes a white waxy covering, arranged in a very regular 



