THE NARCISSUS- OR DAFFODIL-FLY. 



181 



THE NARCISSUS- OR DAFFODIL-FLY (Merodon equestris). 



By Rev. W. Wilks, Sec. R.H.S. 



A discussion of intense interest to Daffodil-growers was initiated by Mr. 

 Percy Williams, of Lanarth, at the meeting of the Daffodil Committee on 

 Tuesday, March 25, 1902. 



A note on this pest will be found in our Jouenal, vol. xxvi. p. 249, 

 which summarises practically all that was known about Merodon equestris 

 up to the present. Mr. Williams was led to make his interesting observa- 

 tions by a conviction that the grub makes its entrance through the base 

 of the bulb, and not, as hitherto imagined, by way of the crown. The first 

 introduction Mr. Williams had to the pest was in February 1901. When 

 noticing that some bulbs in one Daffodil bed had weaker crowns than their 

 fellows, he dug down and examined them, and found that the grub of 

 Merodon had bored into the centre of each of the weaker-crowned bulbs. 

 Without disturbing the roots he found he could distinguish the infested 

 bulbs, from the fact that wherever the grub was present the stumps of the 

 last year's flower and leaf- stalks remained inactive, instead of being 

 replaced by new growth, the weakly growth which had attracted his 

 attention coming, it was found, from the sides instead of from the centre 

 cf the bulb. 



The grub was generally found near the crown of the bulb, apparently 

 making its way towards the surface, and could frequently be extracted 

 with a pair of small pincers without any disturbance of the bulb. In one 

 or two cases the grub had eaten its way into the neighbouring bulb, but 

 as a rule, if the partly eaten bulb was found empty, it was inferred that 

 the grub was in the surrounding earth waiting to hatch into a fly, and in 

 several cases it was actually found resting just under the surface. 



In March two dead grubs were found which had apparently been caught 

 by the frost on the surface. 



Some bulbs were found where the grub had apparently died young, or 

 had early moved on into another bulb, the base of such bulbs showing a 

 nasty wound, but without freshly decomposed matter and in process of 

 healing up instead. This fact strengthened Mr. Williams's opinion that the 

 grub enters a bulb from the base and works upwards. Mr. Williams is 

 also of opinion that by examining the base of each bulb and following up 

 any rotten or dark spot the small grubs may be detected. The dark or 

 rotten spot may, of course, be "basal rot," but he is confident that it is 

 often the result of the presence of Merodon. 



For some time Mr. Williams seems to have failed to identify the fly of 

 Merodon. He therefore sent up a specimen of what he thought was it for 

 identification to the British Museum, and received from Mr. E. E. Austen 

 the following interesting note in reply : — 



The rly you have sent is not a Merodon, but a specimen of the 

 common drone-fly {Eristalis tenax). Merodon and Eristalis are not 

 very similar in appearance, and their respective life-histories and 



