THE SYRPHIDAE OF OHIO 47 



(6) The larvae which Hve in the tissues of many plants must seem- 

 ingly interfere more or less with the normal functions of the plant-body. 

 In some cases they clearly destroy the plant or advance decay, as in cacti. 

 The economic status of the insect in such cases will depend entirely on that 

 of the plants attacked; if it be an obnoxious weed it would result benefi- 

 cally; if in bulbs such as A^arn'ss7{s, Aiiiajyllis and onion, which are exten- 

 sively destroyed in Europe at times, the larvae may become very serious 

 pests. Injury to many other plants may for all practical purposes be con- 

 sidered of no economic importance. 



(7) In this relation the larvae must be accorded whatever degree of 

 importance ordinarily attaches to that scattered group of animals which, 

 by feeding upon decaying organic matter, reduce it to a condition in which 

 it can be more readily assimilated by plants; and at the same time often 

 help to remove materials which may be a menace to health. 



Perhaps this is a suitable place to mention a report, which has so 

 often been given on authority which ought not to be questioned, that it 

 must seemingly be given credence. It is to the effect that the larvae of 

 En'sfalis spp. have been passed alive from the human alimentary canal. 

 "Professor Riley mentioned the sending of E. dimidiatiis in the larval 

 state by Dr. Compton, of Indiana, who stated that they were passed from 

 the bowels of a young woman ; also the recent sending of larvae of JL 

 tenax by Dr. J. A. Lintner to whom they had been sent as having been 

 obtained under similar circumstances." — Lis. Lift\ II, 161, 162. 



These larvae are very tenacious of life. Buckton relates that larvae 

 accidently introduced thru the water of some pulp in a paper-mill, sur- 

 vived the pressure of beaters or rollers u.sed in the manufacture of paper. 

 Gradual immunity to the digestive secretions might be acquired by lixing 

 in human excrement, where they are commonly found, and so, when 

 accidentally swallowed in drinking water, the larvae would be able to with- 

 stand passage thru the stomach and intestines. Is it not possible that, 

 gradually, larvae so introduced might take U]) the parasitic habit in man ? 



Osten Sacken has published an exhaustive study dealing with the 

 ancient superstitions about the spontaneous production and artificial 

 breeding of bees, from the carcasses of oxen. He believes that the oxen- 

 born bees, Biii>onia of the Ancients, were the flies, En'staiis tc)ia.\\ and 

 that the superstitions aro.se because of the occasional breeding of these 

 flies in decaying carcas.ses and their re.semblance to bees. 



(8) The relation of the larvae of VoluccUa and Microdon to the 

 Hymenoptera in whose nests they liv'e, has l)cen rather fully di.scu.ssed 



