ON THE LIFE HISTOEY OP UGIMYA. < 



lot. There is no danger of introducing the eggs of the fly into 

 the silkworm, if every mulberry leaf given to tlie silkworm is examined, 

 and the eggs are removed, if found attached. But this method has 

 only a theoretical value ; it would be utterly impossible to carry it into 

 effect, for it would require an enormous expenditure of time and labor. 

 The only methods which I therefore believe to be practicable are by 

 attending to the modes of planting mulberry trees by which the flies 

 may be prevented from visiting the bushes and depositing their eggs. 



2nd. As a general thing, the flies select for the deposition of 

 their eggs mulberry trees planted on moist or shady grounds or near 

 ponds, marshes, ditches &c. or in the vicinity of the spots where various 

 much branched shrubs grow in numbers or in xmy other places where 

 air currents do not freely circulate. On the other hand, those planted 

 on dry and high grounds or in the neighbourhood of large streams 

 or on spots where air passes freely, are mostly free from the eggs 

 of the fly. On this account, those who desire to plant on new grounds 

 should consider their features from this point of view. 



3rd. In order to prevent the deposition of fly-eggs on the leaves 

 of mulberry trees already planted very close to one another, one or two 

 stumps should be rooted out at regular intervals so as to allow the air 

 to pass freely between the remaining trees. If it is required on the 

 other hand to plant the trees on new grounds, they should be dis- 

 tributed in the ratio of one stump to one Tsubo (6 feet square) or of 

 300 stumps to one Tan (300 Tsubo or 10,800 sq. ft.) 



4th. If two varieties of mulberry trees which sprout at dif- 

 ferent times were planted in alternate rows, there would obviously be 

 freer passage of air through the plantation than if all sprouted simul- 

 taneously. Such a precaution will certainly have a good effect. 



5th. The old and much exhausted trees which bear their leaves 

 crowded on shortened stems are selected most by the flies, so that, if 



