15 



Various directions for spraying are given with descriptions of 

 apparatus and formulae. For kerosene emulsion, 7| U.S. gals, kerosene 

 to 2h lb. hard soap dissolved in 4 U.S. gals, water is recommended. 

 For resin wash, 90 lb. resin, 22| lb. caustic soda (98 per cent.), 1| U.S. 

 gals, fish-oil, 75 U.S. gals, water. For self-boiled lime-sulphur, 30 lb. 

 quick-lime with an equal quantity of sulphur to 100 U.S. gals, water 

 is advocated. 



Otanes y Quesales (F.). The Bean Fly. —Philippine Agriculturist, 

 Los Bonos, vii, no. 1, August 1918, 27 pp., 5 plates. [Received 

 11th November 1918.] 



Agromyza destructor, Malloch (bean-fly) has been doing such damage 

 to growing beans at the College of Agriculture that it is considered 

 likely to become one of the most injurious j^ests of beans. It was 

 first noticed in 1912, but had probably attacked native beans previously 

 both there and in other localities. 



Other species of great economic importance have been reported 

 from other countries. In Australia, Agromyza phaseoli, Coq., mines 

 the stems of growing bean plants and in Ceylon the same species often 

 causes the complete failure of the bean crop. In India, Agroinyza sp. 

 injures the stems of growing peas, and in the United States, A. simplex, 

 Lw., occasionally destroys asparagus by mining the stem. In Java, 

 A. sojae, Zehnt., is reported as damaging Soja, Vigna and Phaseolus 

 by boring into the st«m. 



The adult flies of A. destructor are most abundant at the time of 

 appearance of the first two leaves of the plants. The female punctures 

 the leaves for feeding purposes and also inserts the eggs in these 

 jjunctures. The eggs hatch in two days, the larvae mining under 

 the epidermis on the under- side of the leaves. After a day or two 

 the larvae begin to travel down the stalk, feeding just under its skin. 

 The base of the stalk just above and below the surface of the ground 

 frequently contains several such mines, the result being the decay 

 and eventual death of the plant. The petioles of the leaves and some 

 parts of the skin swell and rupture under the attacks of the larvae. 

 Pupation generally takes place at the base of the stalks under the 

 dried skin. The life-cycle occupies an average of 21 days, being 

 slightly lengthened from December to February, doubtless owing to 

 cold weather. Serious damage is caused only when the plants are 

 young. A set of nine tables records the injury to various plantings 

 of beans and cowpeas. The kidney bean {Phaseolus vulgaris) and the 

 cowpea {Vigna sinensis) are the species preferred for attack, 100 per 

 cent, being frequently damaged in infested areas. An average of 200 

 eggs is laid by one female, all plants accessible being attacked by one 

 individual. Phaseolus lunatus is the most resistant bean observed, 

 and is only attacked at the time of appearance of the first two leaves ; 

 Dolichos lablah and Phaseolus nvungo are also resistant, but to a less 

 degree. The following plants are apparently immune : — Psophocarpus 

 tetragonolohus, Centrosema plumieri, Canavalia ensiformis, Cyamopsis 

 psoraleoides Stizolohium lyoni (velvet bean). Glycine hispida (Soy bean) 

 and Cajanus indicus. Flies have been observed abundantly wherever 

 young susceptible varieties are growing, indicating that they are 

 present in approximately the same numbers throughout the year. 



