INSECTS INJURIOUS TO AGRICULTURE IN JAPAN 71 



in northern Japan, and the adults carry over the winter concealed 

 in rubbish and in other protected places. They emerge from hiberna- 

 tion in the spring and begin feeding, but egg laying does not take 

 place until early July. The eggs are laid in groups of from 15 to 

 20 on the undersides of the leaves and hatch in 10 days. Pupation 

 takes place early in August upon the foliage or stem, and emergence 

 of the adults occurs about one week later. According to Muramatsu, 

 there are three generations per year in Chosen, the first brood of 

 adults emerging the middle of June, the second early in August, and 

 the third late in the season. The larvae feed chiefly during the early 

 morning and in the evening, remaining hidden away during the day. 



E. 28-punctata (185) is found in Honshu, Kyushu, Chosen, and 

 Siberia. In the first-named island there is one generation, rarely 

 two, a year {107), and the habits are the same as those of the preced- 

 ing species. It is most abundant in central and southern Japan. 

 Control is by the collection of the adults. 



According to Hori (35) the two aphicls Omyzus (Ehopalosiphum) 

 persicae and Macrosiphum matsumvuraeanum are serious pests of 

 potato and eggplant in Hokkaido and Honshu. In Hokkaido po- 

 tato mosaic is spread through the agency of both of these species. 

 O. persicae hibernates in the egg stage upon Trifoliwn spp., Arc- 

 tium lappa, and Ga,rthamus twctorius. 



INSECTS AFFECTING SWEETPOTATO 



Of the Lepidoptera attacking sweetpotato in Japan proper the 

 most important species is Ephesia (Catocala) dissimilis, which is 

 commonly found in certain parts of Kyushu and in China. Ac- 

 cording to Oda (139) the yield in the Kagoshima section in 1911 was 

 reduced an average of 3 per cent, though in some years the loss is 

 considerably greater. There are three broods per year, but during 

 the latter part of the season these overlap considerably. The winter 

 is passed in the mature larval or pupal stage in the soil. The first 

 brood of moths appears early in May, and the eggs of these are 

 deposited on the young plants in the seed bed and hatch in about one 

 week. When feeding is complete the larva enters the soil to a 

 depth of 2 or 3 inches, pupates within a cell, and emerges 15 days 

 later, this being in the latter part of July. The third brood of moths 

 appears about the middle of September. This insect is particularly 

 abundant in the fields upon warm, sunny hillsides, and is rarely 

 found in low, damp places or in the mountainous sections.- The 

 collection of adults by lantern traps and sugar baits, and the killing 

 of the pupae by winter plowing are the control measures used. 



The sweetpotato army worm, Scotogramma trifolii (1^5), is a se- 

 rious pest in southern Japan and causes extensive defoliation. There 

 are three broods a year, and the winter is passed as a pupa in the 

 soil. Control is largely effected by the collection of adults at 

 lantern traps and of the larvae by hand. Kerosene emulsion and 

 pyrethrum powder are very effective against the first two larval 

 stages. 



The sweetpotato stem borer, Omphisa anastomosalis (169), occurs 

 in Taiwan and China as a rather minor pest of sweetpotato. The 

 eggs are laid singly on the leaf or petiole, and the larva bores into 

 the roots and tubers, pupating in the burrow, which is filled with 

 excrement. 



