Amaryllis Trouble
Mon, 29 Oct 2007 18:26:34 PDT
On 29 Oct 07, at 20:57, Glen Pace wrote:

> One thing that could be a possibility is that there is an insect infestation 
> of the basal plate.  I have had a larvae of some sort of bug that eats 
> through the basal plate and causes the "shrinking effect" effect you have 
> described, the healthy looking leaves and all.  If the bulbs are taken out 
> of the pots in the fall and the basal plate inspected you may see a tiny 
> hole in the basal plate.  If the bulb is split you can find the larvae 
> inside the bulb eating away.  I have not seen the adult of this larvae, but 
> it will kill a bulb in a few seasons.  I would also suggest putting the 
> bulbs in as much sun as possible during the summer months.
> Sorry, but I do not remember the name of the bug that I am writing about and 
> I am not saying that it is the problem, but I have had the problem with the 
> larvae and know of its capabilities first hand.  I am sure that others on 
> the list can give the name of the menace.

Narcissus flies, the greater and the lesser. They are pervasive here 
in Victoria, BC, Canada, perhaps because the large numbers of feral 
daffodil bulbs growing in neglected places provide reservoirs from 
which the flies emerge to attack garden plants.

All members of the Amaryllidaceae are subject to their depredations, 
but some much more so than others. Cyclamineus hybrid narcissus (e.g. 
'Dove Wings') seem to be resistant, but the triandrus hybrids (e.g. 
'Thalia' and 'Liberty Bells') disappear in one season. Nerine and 
Crinum seem to be resistant, as are Galanthus and Acis, but Leucojum 
vernuum is at least somewhat subject to their depredations.

The cultivated hippeastrum hybrids commonly called amaryllis are 
definitely subject to damage from narcissus flies. If you summer your 
amaryllis outside and you are in an area infested with narcissus 
flies, you should lightly wrap the amaryllis in cheesecloth to 
prevent the flies from reaching the bulbs.

Narcissus flies lay their eggs on the withering foliage at ground 
level, the grub crawls down the outside of the bulb, and then tunnels 
up from within. They are mere flies and can be controlled by nearly 
any standard insecticide (unlike many weevils), but since they are on 
the wing from the first warm days in early May until about the end of 
July, you have to spray (and spray meticulously!) about every two 
weeks over a three month period. Entirely aside from the potential 
environmental impact of this much spraying, it's simply too much work 

I have read that if you backfill the cavities left by withering 
narcissus foliage with fine sand, this blocks the grubs' access to 
the basal plates. However I am skeptical about the efficacy of this 

Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate

on beautiful Vancouver Island

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