582 Agricultural Experiment Station, Ithaca, N. Y. 



extent, by the mere rnecliaiiical action of the water. It is really 

 remarkable that the sand, in Exp. I., was such a perfect filter as to 

 hold the great quantity of arsenic above a depth of three inches for 

 over four months. ] [ If the soil in either experiment had been a homo- 

 geneous^subsoil, where the sun could not have cracked or checked 

 it, it is fair to conclude that no arsenic could have penetrated it. 



II. THE CANKEE-WOEM. 



The canker-worm is one of the most dreaded scourges in west- 

 ern New York. It is an old offender, and yet its appearance in 

 an orchard or on shade trees still awakens as much terror as would 

 the iritroduction of some strange and omnivorous pest from another 

 country. ^The reason why the canker-worm always commands 

 this wholesome respecf^^is because [it^is ^a voracious feeder. It 

 multiplies with astonishing rapidity when it has once established 

 itself upon a plantation. Its work is so apparent that the most 

 careless person is arrested by it. The presence of the canker-worm 

 is an evidence of neglect, and it is at the same time a most efficient 

 reminder of that fact to the owner of the plantation. It is a leaf- 

 eating insect and should, therefore, be dispatched with Paris green. 

 In fact, it is the very insect upon which the first efficient experi- 

 ments were made with that insecticide and from which the recent 

 development of the spraying of trees has come. An insect which 

 has done so much good as to have demonstrated the means of its 

 own destruction and to have given the hint for the annihilation of 

 all its alUes, should be held in pleasant remembrance. 



Yet, the orchardists complain that they cannot kill the canker- 

 worm with poisons. Some persons even declare that its keenest 

 delight is to feed on Paris green. It is well known, however, that 

 the insect is as susceptible to poisons as other leaf-feeding worms, 

 and there are experiments enough on record to show that spraying 

 is capable of wiping out the pest. It is evident, therefore, that the 

 reason why so many people fail to kill it by spraying is because 

 they do not perform the work thoroughly and in season ; and then, 

 it is a fact that the worm very often becomes thoroughly established 

 and settled in an orchard before the orchardist ever notices it, or, at 

 least, before he decides to do anything about it. It is probably im- 

 possible to rid an orchard of the worm in a single season if the pest 

 is so numerous as to devour all the leaves. It should have been 

 destroyed two or three years before such a state of affairs is possible. 



