336 THE ENTOMOLOGIST. 



Food of Eristalis and other Diptera. — As to flies, it has 

 been until now generally admitted that they are exclusively 

 destined to fluid nutriment; but, in the summer of 1867,1 

 was surprised, while observing in my garden an Eristalis 

 tenax upon a flower of CEnothera media, to discover that it 

 was eating the pollen. Resting upon its middle and hind 

 legs, it thrust out its fleshy proboscis like an arm, seized a 

 morsel of pollen with the two valves which terminate the 

 proboscis, and tore it away from the anther. Since the 

 pollen granules of Oenothera are tied together by elastic 

 threads, that bit of pollen torn from the anther was attached 

 to others by a band of threads, and the insect, in order to free 

 its mouth from that inconvenient appendage, began to use its 

 fore legs. Raising both together towards its mouth, it seized 

 between them the cordon of threads, and rapidly rubbing 

 them one against the other, much as we do in washing our 

 hands, succeeded in cutting the threads, and clearing them 

 from its mouth and legs ; then it raised them again, and 

 seized the two valves of the proboscis, thoroughly cleaning 

 them of pollen, and the threads yet adhering to it ; and in 

 about three seconds this work of cleaning was complete. At 

 the same time, the valves of the proboscis, by rubbing against 

 each other, had masticated the morsel of pollen, and had 

 conveyed the single granules into the channel of the labium, 

 whence they were pushed into the mouth. It had hardly 

 finished cleaning its proboscis and eating the first mouthful 

 of pollen when it seized another portion, and repeated each 

 and all the operations 1 have described. It was so intent 

 upon its meal that I was able to observe it in the closest 

 proximity without its manifesting the slightest fear. The 

 quantity of pollen which an Eristalis can devour in this way 

 is surprising. Upon making a section of one and examining 

 the stomach, it appeared very large, and was full of a yellow 

 substance, which consisted of hundreds of thousands of 

 pollen-grains. I have had since then many opportunities to 

 observe this eating of pollen, not only in all the species of 

 Eristalis, but also in the genera Rhingia, Syrphus, Volucella, 

 and Scatophaga. This chewing of pollen alternates with 

 sucking honey, if the flowers have any ; and I am of the 

 opinion that the singular structure of the proboscis of flies 

 cannot be fully explained without taking into account its 



