OP THE FARM AND GARDEN, 379 



crops against the inroads of travelling schools of the in- 

 sects. They were found especially advantageous in much 

 of the ravaged country in a year when there was little or 

 no hay or straw to bum. They are the best available 

 means when the crops are advanced, and when most of 

 the other destructive methods so advisable early in the 

 season can no longer be effectually used. Simple ditches, 

 two feet wide and two feet deep, with perpendicular 

 sides, offer effectual barriers to the young insects. They 

 must, however, be kept in order so that the sides next 

 the fields to be protected are not allowed to wash out or 

 become too hard. They may be kept friable by a brush 

 or rake. 



The young locusts tumble into such a ditch and ac- 

 cumulate and die at the bottom in large quantities. In 

 a few days the stench becomes great, and necessitates the 

 covering up of the mass. In order to keep the main 

 ditch open, therefore, it is best to dig pits or deeper side 

 ditches at short intervals, in which the locusts will accu- 

 mulate and may be buried. If a trench is made around 

 a field about hatching-time, but few locusts will get into 

 that field until they acquire wings, and by that time the 

 principal danger is over, and the insects are fast disap- 

 pearing. If any should hatch within the inclosure, they 

 are easily driven into the ditches dug in different parts of 

 the field. 



Protection bt Barriers. — Where ditches are not 

 easily made, and where lumber is plentiful, a board fence 

 two feet high and with a three-inch batten nailed to the 

 top or side from which the locusts are coming, the edge 

 of it smeared with coal-tar, serves as an effectual bar- 

 rier, and proves useful to protect regions, where, save in 

 exceptionally favorable locations, agriculture can be suc- 

 cessfully carried on only by its aid, and where means are 

 already extensively provided for the artificial irrigation 



