38 INSECTy AFFECTING THE ORA.N8B. 



becomes dark purple at maturity. The serrated hind margin is thin 

 and tinged with yellow. 



The mature females do not entirely fill their scales. When gravid 

 with eggs, their bodies, although much thickened, are reduced in cir- 

 cumference, and in laying they surround themselves with a nearly com- 

 plete circle of eggs. Length of mature female 0.6 mm (0.02 inch). 



Er/gs.The eggs are as large or larger than those of the Long Scale, 

 and resemble them in shape and color. They are nearly ().2 mm (0.008 

 inch) in length, and are more or less amethystine in color. 



Young Larva. The migrating larva is very broadly oval, and mottled 

 with purple. It differs from the larva of related species only in minute 

 details. 



Male. (Fig. 9.) As soon as it be- 

 gins to form its permanent scale, the 

 male insect becomes distinguishable 

 from the female by its more elongate 

 form, and it soon turns to a dark pur- 

 ple-red color. The skin of the second 

 molt is pushed toward the mouth or 

 thrown out of the scale. After shed- 



dill g tlllS skil1 tllG inale illS6Ct 



no. 9.-Prtetorf pergnnOti, male. (After 



comstock.) a pupa of dark red or purple color, 



and has the form of the fly with members folded or abbreviated. 



The perfect insect emerges from the thin outer end of its scale, which, 

 however, has no hinge or flap. The fly is very similar to those of the 

 Kcniis AxpidioiuS) but is shorter and stouter, and has larger eyes than 

 the species of Mylilaspis. The color is purple, mottled, and somewhat 

 p.iler upon the large shield of the upper surface. Length to the tip of 

 the sryh't about equal to that of its scale, O.G mm (0.02 inch). 



Life hfcttory. The young Chaff Scale repeats with slight variations 

 the history of the species already mentioned. After wandering a few 

 hours, it chooses a fixed position, very often underneath a pile of old, 

 dead scales, and in a few days covers itself with a circular shield of 

 white tissue, so thin as to be quite transparent. This covering disap- 

 pears before tlic- time of the first molt. After the molt the females con- 

 struct a circular and the males a linear scale. 



The number of eggs laid is variable. Professor Comstock records in 

 one instance twenty-seven eggs. The average number is sixteen. 



Number of Gentrations. The earlier metamorphoses take place at 

 about the usual intervals of twenty days, but the later periods vary 

 with the seasons, and are greatly accelerated by hot weather. 



The Chaff Scale appears to have one moie brood than the Long Scale. 

 There are four summer generations, but these broods are so greatly 

 confused by unequal development in the females that the limits of each 

 cannot be exactly defined. The first brood in spring and the last brood 



