INSECTS INJURIOUS TO AGRICULTURE IN JAPAN 55 



Japan, Taiwan, Chosen, and China. The injury to sugarcane is 

 caused by the feeding of the young larvae on the younger leaves and 

 the boring by the older ones in the upper part of the stem. Infested 

 plants may be recognized by the time the larvae attain the third 

 stage. These larvae migrate from plant to plant, thus appreciably 

 increasing the amount of injury. Five generations are produced 

 each year, and the egg, larval, and pupal stages cover 12, from 30 

 to 40, and 10 days, respectively. 



Ligyy^us rugiceps is an important pest of sugarcane and both dry 

 and irrigated rice in Taiwan (94, 95), the grubs feeding at the roots 

 and the adults upon the foliage. There is probably one generation 

 each year. Other scarabaeids are also present in considerable num- 

 bers, and in the aggregate their damage is often very great. In 

 1914 the green muscardine fungus (M ' etarrhizium anisopliae 

 Motsch.) was introduced into the island from Hawaii for use against 

 the various soil-inhabiting insects affecting sugarcane. According 

 to Yasukawa (210) from 25 to 33 per cent mortality was effected 

 among adult lamellicorns and from 13 to 30 per cent among the 

 grubs in infected soil. 



According to Oho (140) the scarabaeid beetle Alissonotum impres- 

 sicolle is much the most injurious of this group of insects which 

 attack sugarcane in Taiwan, and extensive damage is done in the 

 southern part of the island. There is one brood a year, the adults 

 emerging from early March and being most abundant in late April 

 and May. The adults bore into the larger roots and the stalk below 

 the soil surface. The larvae in their later stages also feed at the 

 roots. The eggs are laid from late August to the end of October. 



Locusta (Pachytylus) migratoria var. migratoroides (173) mi- 

 grates in large numbers from the Philippine Islands to Taiwan, 

 a distance of 250 miles from the northern island of Luzon, at regular 

 9-year intervals, the first invasion being recorded in 1896. Repro- 

 duction takes place in Taiwan, but the infestation invariably dies 

 out within one or two years. Three broods per year are produced 

 in that locality. 



The most numerous species of Hemiptera attacking sugarcane in 

 Taiwan, as recorded by Schumacher (166), are given in the list of 

 species, the most important being Poophilus costalis^ Kolla albomar- 

 ginata, Nirvana pallida, Cicadula sexnotata, Erythroneura (Zygina) 

 subrufa, and Delphax (Liburnia) furcifera. The lygaeid bug 

 Blissus saccharivorus at times causes extensive injury to sugarcane 

 in Okinawa (38) and is also found in Taiwan and certain parts of 

 Japan proper. There is probably a single brood each year. Ex- 

 tensive feeding by the nymphs and adults results in a characteristic 

 bleaching of the foliage and a great reduction in the sugar content 

 of the stalk. Methods of control recommended are the use of re- 

 sistant varieties, the burning of rubbish, and the distribution of an 

 egg parasite common in that section. 



CORN INSECTS 



Corn is grown to a limited extent throughout Japan and Chosen, 

 and also in Taiwan, but more particularly in northern Honshu and 

 Hokkaido, though it is of much less importance agriculturally than 



