390 Report of the Department of Extomilogy of the 



principal varieties of apples, the moth occurs only in trifling numbers; 

 but it is most severely felt in southern and middle Russia where the 

 dry, continental climate of this region seems to be more favorable 

 for the propagation of the insect. Its distribution is largely con- 

 fined to the area of apple growing, which is bounded by the govern- 

 mental states of Livonia, St. Petersburg and Viatka on the north 

 to Taurida, Saratov and Kursk southward. Unlike padellus this 

 moth occurs in Japan, and according to Kuwana it is very common 

 in the kens or prefectures of Hokkaido, Aomori, Akita, Iwate, 

 Yamagata and Nagano, all of which are in the northern and eastern 

 portions of the kingdom. 



BIOLOGY OF THE ERMINE MOTHS. 

 LIFE STAGES OF padellus. 



Egg. — The eggs are deposited in masses, usually oval in shape, 

 which are elongated in the general direction of the twig on which 

 they are situated. The egg mass appears as a reticulated disk or 

 pellicle, which is flattened but slightly convex, and is closely attached 

 to the bark. The dimensions are generally from three to five milli- 

 meters in length and upwards of four millimeters in width, but the 

 egg masses vary much in size as well as in shape, depending on the 

 number of eggs they contain and their accommodation to the 

 positions on the convex surfaces of the twigs. Not infrequently 

 they very much resemlile a eulecanium scale in its earlier stages of 

 development. The individual egg has the appearance of a flattened, 

 yellow, soft disk, oval in shape, with the central area slightly raised, 

 and marked with longitudinal ribbings. It measures about seven 

 hundred microns wide and eight hundred to nine hundred fifty 

 microns in length. The eggs are arranged in rows and are super- 

 imposed on one another like tiles on a roof, the imbrication being 

 very noticeable under slight magnification. The number of eggs 

 in an assemblage is variable,^ running in some instances to only a 

 few, but ordinarily upwards of fifty to eighty in a mass. At the 

 time of deposition the egg mass is covered with a glutinous sub- 

 stance which on exposure to the air forms a resistant protective 

 covering. This is at first yellow, but with the progress of embryonic 

 development it becomes mottled with red and later turns brownish 

 or greyish brown, thus resembling in color the bark on which the 

 eggs are attached. The eggs are usually placed near a bud of the 

 current year's terminal growth and less frequently on the older 

 wood. 



First larval stage. — Length about 1 mm., ranging from about 

 eight hundred to nine hundred and fifty microns; head, cervical 



' The smallest number of malinellus eggs observed in a cluster on seedlings was nine, 

 and the largest number was eighty-three, while the majority of egg masses had between 

 thirty and forty eggs. 



