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Also agree with IDs. We often see solitary females of H. abrupta walking/flitting around birch trees' leaves just off our deck particularly in August, hunting for the caterpillars that they parasitize (of arctiid (tiger) moths as I recall). Tachinids as a group are believed to breed exclusively by parasitizing other insects, usually as their larvae. They form one of the largest and most difficult families in the Diptera, true flies, -- the life histories of most tachinids would be unknown.
Each antenna in 'higher' flies like this one has three basic sections, the first two of which are relatively stumpy: a basal segment (scape), and a second segment (pedicel). The third, terminal section (flagellum) is variable and represents several segments, by far the largest of which is what you are looking at in the image. It's called the first flagellomere but sometimes also the funiculus. A few more thin segments (2nd flagellomere and beyond, with hairs) stick out from the first, collectively called the arista -- the left one is just visible sticking out from the left funiculus.
The large paired first flagellomeres/funiculi possess surface wind hairs (mechanoreceptors) but mainly are the primary olfactory organs of the fly. They contain many thousands of tiny olfactory receptor neurons buried in open pits recessed below the surface: each sends an individual nerve axon down its antennal nerve to 60+ glomeruli (little spherical nerve centres) in the two antennal lobes at the front of the brain. This was studied initially in the tobacco hornworm sphinx moth (Manduca sexta) but now much more extensively in the fruitfly/vinegar fly Drosophila melanogaster, because of the fancy genetic techniques developed for that fly. Each olfactory receptor neuron there contains a particular genetically coded olfactory receptor protein with a certain associated smell spectrum -- 60+ types of them -- and the axons of all the ones with the same protein converge 'correctly' on the same glomerulus. This is studied both by people interested in coding how smell is transduced and processed in insects/vertebrates (some similarities), and by others who are interested in how the many axons from such a diverse receptor organ can find their way in early development to the correct target glomerulus, to link up there to secondary neurons -- a very basic coding problem in developmental biology throughout the animal kingdom.
Steve (Hfx)
________________________________________
From: naturens-owner@chebucto.ns.ca [naturens-owner@chebucto.ns.ca] on behalf of Hebda, Andrew J [HEBDAAJ@gov.ns.ca]
Sent: Thursday, July 17, 2014 4:31 PM
To: naturens@chebucto.ns.ca
Subject: RE: [NatureNS] tachinid fly question
Concur with both Phil and Dave on antennae and identification
ANdrew..
________________________________________
From: naturens-owner@chebucto.ns.ca [naturens-owner@chebucto.ns.ca] on behalf of Phil Schappert [philjs@eastlink.ca]
Sent: July-17-14 3:44 PM
To: naturens@chebucto.ns.ca
Subject: Re: [NatureNS] tachinid fly question
At 3:14 PM -0300 7/17/14, nancy dowd wrote:
>I submitted this Tachinid Fly to BugGuide for ID:
>https://www.flickr.com/photos/92981528@N08/14677768432/
>
>But meanwhile I am wondering exactly what I am looking at on the
>face. Are the thick black lines the mouthparts for sucking up
>nectar/pollen or? This fly was attracted to the light from the
>window early in the morning, so maybe searching for insects (moths?)
>to lay eggs on.
>
>Nancy
I think this is Hystricia abrupta, Nancy. The thick black lines are
most likely the short, and somewhat downward pointing, antennae.
Phil
--
Phil Schappert, PhD
27 Clovis Ave.
Halifax, NS, B3P 1J3
902-460-8343 (cell)
philschappert.com
imaginaturestudio.ca
philschappert.ca
"Just let imagination lead, reality will follow through..."
(Michael Hedges)
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