74 



Goco (A.). Rice Pests. — Philippine Agric. Rev., Manila, xiv, no. 1, 

 1921, pp. 57-62, 6 plates. [Received 5th December 1921.] 



One of the most important pests of rice in the Philippines is the 

 migratory locust [Locnsta migratoria], for which the only remedy is 

 to destroy the hoppers by driving them into pits. It is suggested 

 that the benefit to be derived from afforestation of wild grass land, 

 although the process would be costly, would be invaluable, as it 

 should be a permanent remedy for locusts, and in addition would 

 prevent floods, regulate the water supply and increase the soil fertility. 

 Another very destructive insect is Leptocorisa acuta (rice bug) [see 

 succeeding paper]. The rice stem-borer, Schoenohins incertellus, Wlk. 

 {punctellus, Z.), causes considerable injury, the infested plants pro- 

 ducing empty, bleached grains. A Dipterous parasite has been 

 observed, and may be the means of holding this moth in check. It is 

 believed that it lives in wild grasses, as it is impossible otherwise for 

 the adult to survive and oviposit during the interval of six months 

 before the next rice season. Clean culture will therefore do much 

 to control it. Important leaf-folders are the Lepidoptera, Melanitis 

 isniene, Cram., which feeds at the ends of folded leaves, but can only 

 live on a few kinds of grass and is largely controlled by a Braconid 

 parasite, and Cnaphalocrocis medinalis, the larva of which lives in a 

 folded leaf and strips the upper surface so that the leaf turns white 

 and dry. There are several parasites and predators that keep these 

 pests in check so that the outbreaks are merely periodical. The 

 caterpillars of Prodenia litura, F., and Spodoptera manritia, Boisd., 

 are usually abundant in dry seasons ; they are seldom considered to 

 be rice pests, but they sometimes cause damage to the seed beds and 

 often lay their eggs there before migrating. These should be collected 

 when they are laid in masses on the upper surface of the leaves. If the 

 eggs are allowed to hatch, the seedUngs should be swept with an insect 

 net. Poisoned bran mash is useful against large larvae. Flooding, 

 where practicable, is the easiest and probably the most effective 

 method against them, but is not much practised. Ditching and 

 rolUng are good measures for preventing migration and for kilHng 

 the larvae. Crop rotation and clean culture will also help to keep 

 down the numbers of these cutworms. 



UicHANCO (L.). The Rice Bug, Leptocorisa acuta, Thunberg, in the 

 Philippines. — Philippine Agric. Rev., Manila, xiv, no. 1, 1921, 

 pp. 87-125, 4 plates. [Received 5th December 1921.] 



The Coreid, Leptocorisa acuta, Thunb. (rice bug) is widely distri- 

 buted in the Philippines, and is generally the most important rice 

 pest there. Adults are more abundant than nymphs in the fields at 

 all seasons. At Los Bafios, where the present studies were made, 

 the bugs were first noticed in large numbers in August and were most 

 abundant during November and December. Injury to rice in the 

 milk stage is caused by all phases of the bug, but as rainy-season rice 

 generally reaches this stage during November and December, it 

 naturally suffers more than the dry-season crop. The effect of infesta- 

 tion is similar to that caused by Schoenobius incertellus, Wlk., empty 

 grains being produced. 



In the laboratory adult male insects lived an average of 62 days 

 and adult females an average of 89. Pairing takes place from 7 to 25 

 days after emergence of the female. Oviposition begins from 



