THE ECONOMIC STATUS OF INSECTS AS A CLASS. 563 



ing plants, repeated with many species and genera, have shown a 

 superior growth and vitality on the part of those subjected to cross fer- 

 tilization of such a degree as to leave not a semblance of a doubt, while 

 in individual cases self-fertilization has been scientifically shown to 

 even result in a deterioration so marked that it has been compared to 

 poisoning. 



In this condition of affairs it at once becomes evident that the good 

 offices of insects in this direction are of incalculable importance, since it 

 must be plain that of the natural agencies by which cross-fertilization 

 of plants is accomplished insects are far and away the most prominent. 

 Every investigation which has been undertaken of recent years, and 

 activity in this field is increasing by leaps and bounds, has shown the 

 most marvelous adaptations between the structure of flowers and the 

 structure of their insect visitants, all in the line of facilitating or really 

 enforcing the collecting and carriage of pollen by flower-visiting insects 

 from one plant to another. An estimate of the numbers of the species 

 of insects engaged in this work would include the forms belonging to 

 whole families and almost orders, and if we could imagine the race of 

 flower-visiting insects wiped out of existence the disastrous effect upon 

 plant growth would be beyond estimate. I am not prepared to state 

 that insects benefit plants in this way to such an extent as to overcome 

 the results of the work of the plant-destroying species, but if it were 

 possible to compare in any way the results of these two classes of work 

 it is safe to say that the effect would be surprising. 



We must, therefore, without going further into detail, place this pol- 

 lenization of plants as one of the very most important beneficial func- 

 tions of insects in their relations to man. 



AS SCAVENGERS. 



Another beneficial function of insects, the importance of which can 

 hardly be overestimated, is their value to humanity in doing away with 

 and rendering innocuous dead matter of both plant and animal origin. 

 This subject has never been discussed without reference to the famous 

 statement by Linnseus that the offspring of three blowflies would 

 destroy the carcass of a horse as quickly as would a lion ; and while 

 the exact statement in its details is open to doubt, still it serves to 

 illustrate in a striking way the good offices of insects, and it is cer- 

 tainly true that after the offspring of the blowfly have finished with 

 the horse's carcass this would be left in a much less offensive condition 

 than after the departure of the lion. 



There are inhabited regions in which the climate is so dry that dead 

 bodies of animals never become offensive, but by natural mummifica- 

 tion remain simply as cumberers of the earth. In such regions insects 

 play little part. Wherever, however, there is sufficient moisture to 

 produce a natural decay, there insects occur in swarms and hasten the 

 destruction of the decomposing mass in a marked degree. Were the 



