INSECTS INJURIOUS TO AGRICULTURE IN JAPAN 49 



late May, the middle of July, and the middle of August, respectively. 

 He states that the eggs are laid singly on the leaves. In the early 

 stages the larvae are markedly gregarious. 



Nymphula vittatis (95) is very common in the rice fields of Japan, 

 but seldom becomes sufficiently abundant to cause appreciable in- 

 jury. The larvae have characteristic cases within which they move 

 about in the water surrounding the base of the plants. They feed 

 upon the roots and softer portions of the stem. 



The sugarcane butterfly, Melanitis leda (95), is common upon rice 

 in southern Japan and Taiwan. There are two generations each 

 year in Kyushu and possibly four in Taiwan. The larvae feed at 

 the leaf margin. The pupa is suspended from the leaf by its caudal 

 tip and has no covering whatever. 



The most important of the Noctuidae attacking rice is Sesamia 

 inf evens (93, 96), which is also found upon sugarcane, millet, and 

 Indian corn. It is of general distribution throughout the Orient 

 from Japan to India, in the latter country being an important pest 

 of various cultivated Gramineae, in which, according to Fletcher, 

 the larvae often bore deep into the roots. In Japan there are three 

 broods a year, the adults appearing in early June, July, and Sep- 

 tember, respectively. Hibernation is by the larval stage in the 

 soil. As distinguished from the other two stem borers of rice in 

 Japan, the eggs of this species are laid within the leaf sheath rather 

 than near the tip, and the larvae feed either within or outside the 

 stem. Pupation takes place between the leaf sheath and the stem. 

 Plowing in winter to destroy the larvae in the soil is the only 

 remedy suggested. 



Naranga aenescens is found commonly throughout Japan, Chosen, 

 Taiwan, and China attacking rice and various grasses. This species 

 has previously been referred to in literature as N. diffusa, but ac- 

 cording to Okamoto (150) this latter is an Indian species not found 

 in Japan. His account of the life history (149) gives two broods 

 per year, the adults appearing in early June and at the end of 

 July. The pupae of the second brood pass the winter in the soil. 

 The eggs are laid in masses of 30 or more on the underside of the 

 leaves and hatch in about five days, after which the larvae feed 

 upon the leaf tissue. Pupation occurs within a chamber formed by 

 folding a leaf upon itself and binding it with silken strands. The 

 adults may be captured by the use of lantern traps. This is a minor 

 pest in Japan and India, but it is one of the most important of 

 rice pests in certain sections of China. 



The hesperiid Parnara guttata (95) occurs upon rice and bamboo 

 on all the islands of Japan except Hokkaido, and in Chosen, China, 

 Manchuria, and Siberia. There are 2 generations a year at Tokyo, 

 3 in Kyushu, and 3 or 5 in Taiwan. At Tokyo the adults appear 

 early in June and in late August and September. The larvae of 

 the first generation feed upon the foliage of rice and those of the 

 second upon bamboo. Hibernation is in the larval stage. 



The chrysomelid beetle Lema melanopa is at times found abun- 

 dantly in some districts of Hokkaido (S3), as well as in parts of 

 Honshu, and much damage may be done to rice. One generation is 

 produced each year, and the winter is passed in the adult form in 

 rubbish piles and in other sheltered places. These adults become 

 55059—31 4 



