COMMONPLACE NOTES. 



249 



COMMONPLACE NOTES. 

 By the Secretary and the Superintendent. 



. The Narcissus Fly — Merodon equestris, F. 



The enormous increase in recent years of the growth of Daffodils has 

 brought with it a terrible increase in the number and distribution of this 

 pest. Time was when it was quite unknown amongst us, but it has 

 undoubtedly been imported from Holland and also, to my own knowledge^ 

 from Spain, as I once found no fewer than seven young grubs of the fly in 

 a singla imported bulb of Johnstoni, " Queen of Spain." Since those- 

 days it has increased with great rapidity, and is now far more generally 

 existent amongst collections of Daffodils than the owners are aware of or 

 are willing to admit. A knowledge of the beast and how to deal with 

 him have therefore become matters of considerable importance. 



The fly was first noted by Keaumur in 1738, but at that time it had 

 probably not spread further northwards than the centre of France, and 

 even there it was rare ; and it was only in 1840 that it was noticed as a 

 pest in Holland, and was handed on in due course to England and even 

 America. In 1885 a monograph on the fly was published in Haarlem by 

 Dr. J. Eitzema Bos, Professor of Agriculture at Wageningen, and this 

 continues to be the standard authority. He tells us that the female fly, 

 emerging from the chrysalis in May, may live until July and lay 100 eggs 

 in that time, one by one, separately, throughout a month at least, laying 

 them in the soil around the bulbs and amongst the foliage. He says 

 that a few days after observing this he found a young grub on the 

 outside of a bulb, but he did not see it bore itself a hole into the bulb. 

 Reaumur, however, says that the grub enters the upper part of the bulb, 

 and quits it, when full grown, at the base. This may be its general 

 procedure, but it is not always so, for Dr. Bos says that, after examining 

 more than a thousand bulbs attacked by the grubs, he found several which 

 had only one hole, and that at the junction of the base of the bulb with 

 the enveloping scales or coats, and also some which had no hole at all 

 externally but yet contained a grub. This I also can confirm from my 

 own frequent observation. In explanation Dr. Bos suggests that some- 

 times the hole of entrance is so minute when the grub has just emerged 

 from the egg that the wounded tissue of the bulb has grown up again, 

 leaving no trace. This appears to me unlikely, as the excreta of the 

 beast would of itself, I think, be sufficient to keep open any hole once 

 made, for it is distinctly acid. He then gives what I think is the true 

 explanation — viz., that the young grub on emerging from the egg works 

 its way down the tissue of the leaves till it reaches the bulb and pene- 

 trates between its coats, and thence begins to bore its tunnels, and so 

 gradually descends towards the base, where, as a rule, it bores a way 

 through, and perhaps sometimes escapes, though sometimes it seems as if 

 it turned round at the base and bored its way up th(» other side of the bulb, 

 and emerged almost exactly at the spot where it entered. One of the two 



