March, 1912.] 



223 



Plant Sanitation. 



very absorbent soils) to every square 

 yard of soil surface. For deep beds the 

 quantity must be increased. Care must 

 be taken that all parts of the soil are 

 reached and thoroughly wetted by the 

 solution. CJ pon the thoroughness with 

 which it is done depends largely the 

 success of the process. After the for- 

 maldehyde solution has soaked in the 

 soil should be thoroughly stirred, so 

 that all parts may be exposed to the 

 disinfectant. Before setting into the 

 soil any plants or sowing any seeds the 

 excess of formaldehyde must be allowed 

 to escape by evaporation or, if neces- 

 sary, be washed out by flooding the bed. 

 The former is preferable. The writer 

 has not found the germination of seeds 

 interfered with when 10 days are allowed 

 to elapse between the treatment and 

 the sowing of the seeds, especially if the 

 soil be allowed to become rather dry 

 and be stirred in the meanwhile. The 

 treatment of plants already attacked is 

 almost impossible. Means that will dis- 

 troy the nematodes are mostly injurious 

 to the plants containing them." 



THE VALUE OF BIRDS TO MAN. 



(From Nature, No. 2109, Vol. 88, 



December 21, 1911.) 

 Vegetation is the prime requisite for 

 the perpetuity of all other forms of life 

 upon the earth. The greatest known 

 enemy to vegetation is insect life, while 

 bird life, by virtue of its predominating 

 insect diet, wields a most important 

 balance of power against the ravages of 

 this the chief pest of vegetation. 



The number of insect species is greater 

 by far than that of the species of all 

 other living creatures combined. The 

 voracity of insect life is as astonishing 

 as its power of reproduction. Many 

 caterpillars consume twice their weight 

 in leaves per day, which corresponds to 

 a horse eating daily a ton of hay. 



The development of young birds is so 

 lapid, and the demand upon the vitality 

 of older ones so great, that an enormous 

 amount of food is necessary to sustain 

 the vital processes. Digestion is exceed- 

 ingly rapid in birds ; and they feed for 

 the most part throughout the day, 

 especially when rearing young. The 

 number of insects daily passed into the 

 insatiable maws of the nestlings during 

 the period almost exceeds belief. But 

 the most valuable services of the adult 

 bird are rendered when it is feeding in 

 winter or early spring, for then it des- 

 troys countless numbers of insects in 

 the embryo state, and thus prevents 



myriads of depredators from coming 

 forth. Grave and far-reaching results 

 invariably follow the suppression of this 

 perennial regulative influence which is 

 exerted by birds individually every- 

 where as a check on insect life. 



Forest trees have their natural insect 

 foes, to which they give food and 

 shelter ; and these insects in turn have 

 their natural enemies among the birds, 

 to which the tree also gives food and 

 shelter. Birds are not only essential to 

 the well-being of the tree, but the tree is 

 necessary to the life of the bird. It is 

 because of this most delicate adjustment 

 between the tree, the insect, and the 

 bird that Mr. Frank M. Chapman's 

 statement '* that it can be clearly de- 

 monstrated that if we should lose our 

 birds we should also lose our forests," 

 must be regarded as profoundly true. 

 Call the bird in the orchard an evil if 

 you will. But it is a necessary evil, and 

 the fruit-grower must make up his mind 

 to pay the bird its wages, even though 

 at times they may seem exorbitant. 



Each season, until hay-making com- 

 mences, the grass offers cover and 

 shelter for the nests of such birds as 

 breed on the ground. The fields also 

 provide food for birds, and for the 

 insects on which birds feed. Where the 

 birds of the field are undisturbed they 

 tend to hold the grass insects in check. 

 On the other hand, when the numbers 

 of birds in the field are, for any reason, 

 insufficient, the insects increase. 



Without birds grass could not be 

 grown. The grub of a single species of 

 beetle, if unchecked, could destroy all 

 the grass roots of our meadows, or any 

 of the several species of cut-worms 

 might be sufficient to destroy all the 

 verdure above ground. 



The destructive habits of the small 

 rodents, which are the natural prey of 

 hawks, and owls, are much the same all 

 the world round. Here in England— 

 though on account of their small size 

 and secretive habits they are often un- 

 discerned by man's dull eyes — they 

 swarm in such numbers in the fields and 

 hedgerows that the damage they do 

 must prove a steady drain on the re- 

 sources of the farmer. The number of 

 small rodents eaten by the rapacious 

 birds is almost as remarkable in propor- 

 tion to their size as is the number of 

 insects eaten by small insectivorous 

 birds. 



The young of hawks and owls remain 

 a long time in the nest, and require a 

 great quantity of food. During this 

 period the resources of the parents^must 

 be taxed excessively in the effort to 



