1921 ENTOMOLOGICAL SOCIETY. 53 



The Cost of Application. 



Per 24,000 plants. 



HgCL, 2y 2 lbs. at $4.00 per lb $ 10 00 



1st Application: Time: 20 hours, 1 man at 50c per hr 10 00 



HgCl,, 3 lbs. at $4.00 per lb. 12 00 



2nd Application: Time: as above 10 00 



3rd Application: HgC1 * 3 lbs - at $ 4 - 00 P er lb • • • 12 00 



Time: As above 10 00 



Time for preparation, Hauling, etc., 3 00 



Total Cost: $ 67 00 



The total cost of three applications approximates one cent for four plants, 

 while for four applications the cost would be one cent for three plants. 



INTER-RELATIONS IN NATURE. 

 W. Lochhead, Macdonald College, Que. 



To the economic entomologist the investigation of the "Inter-relations in 

 Nature" should be one of the most important fields of study, for abundant 

 evidence has been collected to show that all nature is a vast system of linkages, 

 one part dependent upon another in an- intricate web of life, and that disturbances 

 in one portion of the system are followed by disturbances in another. To Darwin, 

 more tha-n any other person, science is indebted for the elaboration of the idea 

 and for the clear demonstration of its practical importance. 



Since Darwin's time the number of examples of inter-relations has been 

 greatly extended through the observations of thousands of investigators. In 

 our boyhood days we were accustomed to rhyme the chain of events in "The House 

 that Jack Built,'-' which ends with "This is the cat that killed the rat that ate 

 the malt that lay in the house that Jack built." In Nature many such chains 

 have been unravelled, binding animal with animal, and animals with plants and 

 these again with the inorganic world. Man eats the fishes that eat Crustacea 

 that eat infusoria that c-at bacteria that feed on decaying organic matter in 

 some pond. 



The purpose of this paper is to discuss briefly, or rather to point out those 

 inter-Tel a ti on s in nature that have to do more particularly with insect life. The 

 subject is a big one, so that much more must necessarily be left unsaid than can 

 possibly be said in a paper on this occasion. 



The following relationships will be discussed. 



1. Insects in relation to insects. 



2. Insects in relation to other animals. 



3. Insects in relation to plants, including bacteria and fungi. 



4. Insects in relation to inorganic nature. 



1. Insects in Relation to Insects. 



The part played by predatory and parasitic insects in the regulation of 

 insect life has been frequently discussed at these meetings. The topic is a very 

 important one and studies are being carried on at many stations, and none better 

 than those by Mr. Tothill, of the Dominion Entomological Laboratory at Frederic- 



