INSECTS INJURIOUS TO AGRICULTURE IN JAPAN 57 



the blades. The control method employed is the digging of ditches 

 around the borders of the fields into which the larvae fall when 

 searching for a hiding place during the day or when migrating 

 from one field to another. 



Sesamia inf evens (95) attacks millet, rice, wheat, and oats and is 

 of general distribution. There are two, and at times three, genera- 

 tions a year, and the winter is passed either in the pupal stage or 

 as an adult moth. The damage to millet is largely due to the feed- 

 ing of the larvae upon the roots. The collection of adult moths by 

 lantern trap is advocated as a means of control. 



The European corn borer, Pyrausta nubilalis, is a very common 

 pest of millet throughout Japan and Chosen and on the whole is 

 of more importance as a pest of this crop than of corn. Its life 

 history is discussed among the enemies of the latter crop. 



CLOVER INSECTS 



Upon field clover the insects on record are Golias hyale polio - 

 graphus, Barathra brassicae, Ghloridea dipsacea, Euxoa segetis, 

 Maladera (Aserica) orientalis, Popillia japonica, and Luperodes dis- 

 crepans. The more important of these are the three species of 

 Noctuiclae. 



FLAX INSECTS 



The insect species found attacking flax in Japan are Agrotis 

 c-nigrwm, Barathra brassica, and Ghloridea dipsaoea, of which the 

 last two are discussed as pests of other crops. 



HEMP INSECTS 



Of the insects affecting hemp in Japan and Chosen the cerambycid 

 Thyestilla gebleri, the chrysomelid Haltica flavicomis, the noctuid 

 moth Barathra brassicae, and the nymphalids Polygonia c-awreum 

 and Pyrameis indica indica are the most important. 



T. gebleri (191) is a particularly serious pest in Chosen. There 

 is one brood each year, and the adults appear during June. The 

 eggs are usually laid singly in the stalk about 5 or 6 inches below the 

 first node. Upon hatching the larva burrows about in the stem, 

 usually descending from the point of entrance, and makes a hole in 

 the outer wall of the stalk from 5 to 8 inches above the surface of the 

 ground, through which the excrement is ejected from the burrow. 

 Control is effected by the burning of infested stalks. 



No information is available regarding Haltica flavicornis; and 

 Barathra brassioae, the remaining species of major importance, is 

 dealt with as a pest of truck crops (p. 68). 



The nymphalid Pyrameis indica indica (95) occurs in. practically 

 all sections of Japan and in Chosen, Taiwan, and China as well. 

 There are two generations each year, and the winter is passed in the 

 adult stage. The eggs are laid on the undersides of the leaves. 

 Adult moths are present in the field throughout the season from June 

 to October. Another species, P. cardm jayyonica, has a similar dis- 

 tribution and life history. 



Polygonia c-awrewm (95) is commonly found upon hemp in 

 Honshu, Kyushu, and Taiwan, but is not known to occur in Hokkaido. 

 In central Japan two generations are produced each year, whereas 

 there are three in Taiwan. 



