50 CIECULAIl 16 8, U. S. DEPARTMENT OF AGRICULTURE 



active in late May and June and feed upon leaves in the seed bed and 

 main fields. The eggs are laid in masses of from 20 to 30 upon the 

 leaves, and hatch in 11 or 12 days. The larvae feed upon the epi- 

 dermis of the leaf, causing the foliage to assume a bleached appear- 

 ance, and are distinguished by their carrying a considerable mass of 

 excrement dorsally upon the body. This stage covers from 10 to 

 14 clays. The pupae are formed in white cocoons upon the leaves, 

 this stage occupying 17 or 18 days, the adults emerging in July 

 and August. In the paddy fields control may be effected by the 

 use of a floating tray into which the larvae and adults are knocked 

 from the plants. The best results are secured on cloudy or rainy 

 days when there is no wind. This is the species referred to in 

 literature previous to Murata and Ikeda's publication (110) as 

 L. tristis Herbst. 



Another chrysomelid which is quite common in Chosen, though 

 not a serious pest, is Donacia aeraria (8), the larvae of which feed at 

 the roots and prevent the proper ripening of the grain. There is one 

 brood a year, and the winter is passed by the larvae in the soil. 

 These pupate in June, and the adults appear early in July. The 

 food plant of the adult is Potamogeton polygonifolius Pourr, a weed 

 which grows in the paddy fields. The eggs are laid on the underside 

 of the foliage of this plant, and upon hatching the larvae immedi- 

 ately go down to the roots of the rice and begin feeding at the base 

 of the stalk. 



The hispid beetle Monochirus (Hispa) callicanthus (95, 108) 

 occurs in both Japan and Taiwan and is a serious pest of rice in the 

 latter island. There are five generations each year in Taiwan, and 

 the winter is passed in the adult stage. The eggs of the first gen- 

 eration are laid in the leaves in the seed bed, and at times consid- 

 erable damage is done. The eggs hatch in from 6 to 13 days, and 

 the larvae mine in the leaves. Pupation occurs in the mine. The 

 later generations are produced in the field following transplanting. 



A curculionid, E chinocnemus bipimctatus (8) , is also found, though 

 not as a serious pest, upon rice in Chosen and southern Hokkaido. 

 One brood is produced each year, and the adults appear in late 

 June and early July. The eggs are laid in groups of three or four in 

 a hole made by the female beetle in the stem about 1 inch above the 

 surface of the water. These hatch in five or six days, and the young 

 larvae descend into the soil and feed at the roots. This prevents 

 the proper maturing of the crop. The winter is passed in the larval 

 stage, and pupation occurs in early June. Another species of this 

 genus (E. squameus) attacks rice in Japan, Taiwan, and China, 

 and its habits are similar to those of the above species. 



The acridid Oxya velox (96) is found in central and southern 

 Japan, Chosen, Taiwan, and China and attacks wheat, sugarcane, and 

 cotton as well as rice. It does considerable damage at times by feed- 

 ing upon the young plants in the field and is particularly injurious 

 during dry periods. There is one generation a year, and the winter 

 is passed in the egg stage in the soil of the ridges and embankments 

 bordering the field. The collection or destruction of the eggs by cul- 

 tivation during the winter is recommended for control. In India, 

 according to Y. Ramchandra Rao, this species is largely a marsh in- 

 sect and is primarily a pest of rice, though attacking also cotton and 



