The Alarm of Insects and Fungi. 21 



an area of high pressure. It is evident, too, that 

 no amount of legislative enactment could have stayed 

 the dispersion unless it should have forbidden the 

 planting of apple trees. 



As a matter of practice, the energetic and intel- 

 ligent fruit-grower will think last and least of the 

 parasite factor when locating his plantation, for 

 this factor is variable and migratory, and, moreover, 

 there are means of keeping most fruit pests under 

 control. Insects and fungi are apt to be bugbears 

 sometimes literal bugbears to the fruit-grower; but, 

 after all, they are rarely to be counted upon as per- 

 manent factors, and they are the direct and perhaps 

 the most efficient means of keeping the farmer in a 

 state of mental alertness. There are a few cases, of 

 course, to which these remarks will not well apply, 

 but they are clearly exceptions. One of these is 

 the dreaded nematode root -knot of the southern 

 states, and one might seriously hesitate in planting 

 peaches where the ground does not freeze deep 

 enough to destroy the pest. The professional ex- 

 perimenters can determine the course of the life- 

 histories of the various pests, and can point out 

 their most vulnerable points, and may even devise 

 general means for their eradication; but the final 

 application of this knowledge is a local problem, 

 which each man must work out for himself. Laws 

 are generally of little avail for the destruction of 

 pests, except in those few cases in which disease is 

 more or less permanent or perennial, and in which 

 there is no practicable recourse but to destroy the 



