246 BULLETIN UNIV'ERSITY OF MONTANA 



living and eventually would become distinct, owing their very existence to 

 an accidental similarity of sports. Each generation tends to make the 

 resemblance greater as the unprotected ones would be more likely to be 

 eaten by hungry birds. We therefore call this a case of insect protective 

 mimicry. It is probably the best case known. The manner in which the 

 species arose teaches Darwin's great doctrine of the survival of the fit- 

 test and explains what he means by natural selection. Without this great 

 key to the secrets of nature before the time of Darwin man was unable 

 to explain many great biological problems, as for example the existence 

 of related species and the enormous waste of life in arriving at maturity. 

 The law of survival of the fittest solves to the satisfaction of many these 

 great problems. The animal takes no conscious part in the great scheme 

 of nature. It takes no thought as to how it is clothed or fed. The un- 

 alterable laws of the universe are at work upon it, but it need not know 

 or care. 



Another line of counterfeiters of very great interest are the numerous 

 unarmed insects who wear the uniforms of the wasps or bees. We need 

 not go into the subject very deeply since it is almost a parallel case to the 

 one given at length above. It is of obvious benefit to a defenseless fly 

 to wear the yellow sash of a bee and thereby escape attacks of enemies 

 w^hich fear the sting of the bee. Many such can be found on the flowers 

 almost any sunshiny day in summer. There is a family of flies that 

 especially enjoys this disguise and feeds on the nectar of flowers, sucking 

 through their long slender probosces. Since they aid in cross-fertilization 

 as much as would a true bee I do not know that we should condemn their 

 deception too severely. We may look upon them as harmless masquer- 

 aders. 



While we admire the cunning in nature which protects so many help- 

 less and innocent ones from injury, what shall we say of those rascals 

 who wear the uniform of the bee, not for protection to themselves, but 

 for the purpose of being better able to steal upon their victims. Many a 

 tragedy in insect life occurs in about this way. A strong two-winged fly 

 looking very much like a bumble bee in size and color and differ- 

 ing slightly in the buzz of his wings alights on a clover blossom and 

 settles down to await a victim. Soon a heavily laden bumble bee alights 

 upon a neighboring clover head wholly unsuspecting the counterfeit bee 

 on the other blossom. Like most honest people he has little time to 

 harbor suspicion of evil from one of his own kind. The villain squares 

 himself for a jump through the air. A second later he alights upon th6 

 back of his victim. He holds the dangerous abdomen with its deadly 

 sting securely in his bristling legs, and punctures with his strong beak 

 the shiny armor on the bees thorax. In a minute it is all over, and. drop- 

 ping the lifeless victim, he begins to clean himself after the manner of 

 the fly family. I have his picture for the rogue's gallery. (Plate LI.) See 

 how much like a bee he is even with wings and legs spread to show the 

 differences. Gibson has told the Syrphus fly story especially well in his 

 "Sharp Eyes." There is a large number of the robber flies who mimmic 

 for aggressive purposes. 



Why are all small boys afraid of a dragonfly? The boy believes the 



