348 



A AT ECONOMIC ENTOMOLOGY. 



Fig. 399. 



vestiture is confined to the thorax or trunk, and such species are 

 sometimes of use in pollenizing flowers. I have found several 

 species about fruit-blossoms in spring, moving from flower to 

 flower, and, adhering to the vestiture, I have found pollen grains 

 in considerable number ; so the insects are probablv of some 

 importance in this direction. We have one very large species, 

 Eristalis tenax, appearing late in fall, often in houses, and so 

 closely resembling a honey-bee as to be generally mistaken for 

 one ; for which reason it has been called the " drone-fly." It is 

 frequent in greenhouses about the time 

 that chrysanthemums are in bloom, and 

 gardeners have assured me that pollen- 

 izing this flower is done by it entirely ; 

 hence they call it ' ' chrysanthemum 

 fly." It is not at ail unlikely that this 

 is the case ; indeed, it is even proba- 

 ble, though sufliciently direct obser\^a- 

 tions have not as yet been made in the 

 matter. In this connection it is inter- 

 esting to find that the body vestiture 

 of the Syrphids is often composed of 

 spurred and branched hair, similar to 

 that found in bees, and in the ''drone- 

 fly" this character is especialty marked. 



As widely divergent as the flies 

 themselves are the larvae and their 

 feeding habits. In fact, there is no sort 

 of agreement ; and while some are pre- 

 daceous, feeding upon plant-Uce or 

 other insects, many feed in living or 

 decaying vegetable substances, or in 

 the foulest excrementitious material. 

 Those forms that most concern the agri- 

 culturist are the feeders on plant-lice, 

 and these may be found at almost any 

 time during the summer in almost e\'ery 

 aphid colony, busily engaged in lessening its numbers. The 

 larvse are easily overlooked, as they are usually green or yel- 

 lowish in color, like the insects amonq- which thev feed. They 



1 



^^^^ 



Body vestiture of Eristalis 

 tenax : a, entire hair; b, c, d, 

 parts of same ; all greatly en- 

 larged. 



