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small group of 8 at Mt Uniacke.  I don't know if
Hi Dave,
Galling as it might be, I fear that you have made a headstone out of a footnote.
In the meantime as a non-botanist, I have half-educated myself that Knapweed and Ironweed are not the same thing, and that the latter is a rather ambiguous name that could be used for several plants. This is why we should all prefer the Latinized binomial scheme, as Jim sometimes reminds us.
The fly is Eurosta solidaginis (dipteran family Tephritidae, 'picture wing flies' or 'true fruit flies'), and I assumed without proper identification that I'd found galls on the common Canadian species Solidago canadensis. Tephritids are often very specific as to host species, but in his recent 'Flies' book, Marshall says only that the host plant for this fly is Solidago sp., indicating that more than one Solidago species can be attacked. This is supported somewhat on BugGuide, where in one image of this fly it is stated that it was found on S. altissima. To see pictures of the adult and some cut-open galls, type in 'Eurosta' into the BugGuide search box, which brings up a lot of images, about 4 of which are adult Eurosta solidaginis. Or, directly
http://bugguide.net/node/view/267878
other images are /15770, /391405, & /915045
Your 1951 larval description sounds likely right on, except that an adult fly with 21 antennomeres would have to be 'lower' Diptera (Nematocera) -- while the number varies a bit, none of the higher Diptera-Brachycera including tephritids have anything like that many antennomeres. Another tephritid species also inhabits goldenrod, Eutreta novaeborecensis, though according to Marshall lives in the rhizomes, not in the stems. Gall midges (Cecidomyiidae) do have many-segmented antennae, but are small and I haven't seen anything saying they colonize goldenrod, but then the habits of many are unknown.
A better idea than mine about using short-term refrigeration was mentioned by someone on BugGuide, who harvested some stems with galls, presumably after the growing season had ended so no more nutrition was being served up by the plant. The correspondent kept them outdoors over winter but in protective custody to be sure to see the adults emerge in April or so (difficult to find them in the wild). This would take longer, but I might try to collect some in November, if I can find a few then before the first snow. I couldn't see any plants sticking out of a foot of snow on the hill at Mt Uniacke, in February this year, on a short diversion from eagle-viewing at Sheffield Mills.
Steve (Hfx)
________________________________________
From: naturens-owner@chebucto.ns.ca [naturens-owner@chebucto.ns.ca] on behalf of David & Alison Webster [dwebster@glinx.com]
Sent: Thursday, August 7, 2014 9:50 AM
To: naturens@chebucto.ns.ca
Subject: Re: [NatureNS] Fall Dandelion, ants
Hi Steve & All, Aug 7, 2014
That is an awfully long preamble just to point out a spelling error !
Knapweed; yes.
What is that fly called ?
I made some drawings in 1951 of a very fat larva (3.6 mm long, March 14)
and pupa (3.6 mm long, April 20) from a 'gall on unknown plant' which I
subsequenty learned to be Goldenrod. Below this is an unfinished drawing of
an adult fly (4.5 mm long, 21 antennomeres, reduced wing venation, April 26)
with location unspecified. So perhaps from a similar gall.
These galls are easier to find after leaves have shed and are (were ?)
reasonably common in the Kentville area. Are they found on all Goldenrods or
on a select few species ?
Yt, Dave Webster, Kentville
----- Original Message -----
From: "Stephen Shaw" <srshaw@Dal.Ca>
To: <naturens@chebucto.ns.ca>
Sent: Wednesday, August 06, 2014 10:06 PM
Subject: RE: [NatureNS] Fall Dandelion, ants
> Hi Dave * 2 and others,
> Earlier, last year, Fred Schueler mentioned a fly that makes galls in
> golden rod stems, and that has an interesting life history. The larva
> overwinters in the gall during the freeze-up, but according to the Storeys
> makes protective antifreezes, so is able to survive, eventually pupate and
> emerge successfully the following spring. The adult is figured in Steve
> Marshall's recent compendious 'Flies' book, that I'd also endorse
> enthusiastically. The Golden Rod Fly can't fly very well or at all, so if
> its clump of golden rod is an isolated stand it may remain confined there
> as if marooned on an island. Last year I examined a very large
> interconnected stand of the plant on the seaward side of York Redoubt (old
> fort outside Halifax) that looked like prime real estate for the fly, but
> didn't find any galls at all.
>
> In the Mt Uniacke House grounds the weekend before last the golden rod
> flowers (popular with flies) were just coming out, and I examined ~15
> isolated stands of the plant, probably averaging 20-30 feet separation.
> Only one had a number of galls (8), another had one, and the rest had
> none. Has anyone in their local travels come across larger numbers of
> galls anywhere? They are quite obvious, greenish-yellow like the stem and
> placed about 3/4 of the way up it, and about 1.5 cm in diameter. I'd
> like to collect a few specimens but don't want to decimate the small group
> of 8 at Mt Uniacke. I don't know if it is at all realistic, but a few
> weeks with the gall in the fridge might possibly be enough to simulate
> winter and hasten development of the larva to pupa, and stimulate
> emergence in a month or so, without me having to wait until next Spring.
> Steve (Hfx)
> P.S. The only other insect-attractive flowerhead abundant at Mt U was the
> purplish thistle-like 'Ironweed' (the name I was given). Whether or not
> it is the same species, shouldn't Knapweed be spelled with a 'K'?
> ________________________________________
> From: naturens-owner@chebucto.ns.ca [naturens-owner@chebucto.ns.ca] on
> behalf of David & Alison Webster [dwebster@glinx.com]
> Sent: Wednesday, August 6, 2014 7:12 PM
> To: NatureNS@chebucto.ns.ca
> Subject: [NatureNS] Fall Dandelion, ants
>
> Dear All, Aug 6, 2014
> Gnapweed (Centaurea nigra) is just about over now in the yard and Wild
> Carrot (Daucus carota) is half spent so Fall Dandelion (Leontodon
> autumnalis) has become a prefered spot for feeding; 4-5 species of small
> Bees loaded with pollen this morning. White Clover continues to feed the
> odd Bumble Bee.
>
> I don't recall having noticed this previously but the most recently
> expanded umbels of WC (which also had more insects than older umbels) were
> facing the sun. Also late this afternoon all of the L. autumnalis flowers
> were closed up tight; presum