# Inconsistent results in my hydei cultures?



## serial hobbiest (Mar 5, 2017)

I'm trying to get a hang on this hydei culturing thing before getting my frogs at the end of the month. I'm getting a bit anxious here, because for the second time in my two months or so of practice, I'm going to have no flies available for feeding. The first time this happened was an obvious mistake, as I was off camping on the weekend when I usually start a new culture. I forgot about it, and consequently ended up with a week long gap in production. Since then, I've been back on schedule with weekly (give or take a day or two) culturing.

On Jun 23, I figured I'd better make two. I had two cultures that were made 5 days apart, that were both booming- well the older one was on its way out by the looks of things. So anyway, I made one culture seeded with flies from the freshy booming culture, and one seeded from the older one which was probably heading toward a population crash. Interestingly, today only the culture seeded with "fresh" flies is rocking with maggots, but the other barely shows signs of anything going on- not even that yellow blanket (eggs? yeast? both?) that grows across the surface in the first week. I'll admit I regrettably didn't measure the water I used- I only eyeballed it, as I was aiming for something less soupy- another issue I'm trying to address.* Anyways, is it more likely that the issue of the lagging culture is too dry, rather than an issue with the seed flies?*

Going back a week further, I have a Jun 17 culture that seems to be almost a week behind schedule. As of today, it's 19 days old. It's rocking with tiny maggots, and just a few big ones- It looks to be approximately at the same stage as the "fresh fly" Jun 23 culture, actually. So obviously I'll have no emergence from this culture this week, and my imaginary frogs will go hungry again. Realizing this issue yesterday (Wednesday), I seeded a new culture from my oldest culture which was beginning to crash- a population crash I presume. On Saturday, this culture was all fine, and I seeded a new culture from it then as well. Given my experience I've been describing here, I won't be surprised if my older Saturday culture actually booms before the one I made just yesterday. 

I suppose I should be dumping flies on a regular basis, as if I were feeding, to promote some longevity in my cultures. I haven't been doing this on account that I only care that I have some seed flies each week- I just never considered that *flies harvested from over-populated/ crashing cultures might have some reproductive issues*, as what seems might be the case. *Can anyone verify my speculation? What is the underlying cause of a population crash? Why does it happen? What are the flies actually dying of when this occurs?*

-Jason


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## Yazz (Oct 30, 2016)

Jason,

First off, measure the ingredients, no eyeballing. 

Seed your new culture from the first bloom of flies. They are the most vigorous. They bloom when they bloom, so don't go by the calendar, look at what is happening with the flies.

If the flies get overpopulated, they get stressed out and die. Take out the amount of flies you would need for your imaginary frogs. Be it every day, or whatever their feeding schedule will be. 

There are people here that know more than I. Hope they chime in too.


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## Ed (Sep 19, 2004)

Yazz said:


> Seed your new culture from the first bloom of flies. They are the most vigorous. They bloom when they bloom, so don't go by the calendar, look at what is happening with the flies.
> 
> If the flies get overpopulated, they get stressed out and die.


No and No... those are not supported by anything and in fact what is known about how the flies behave in cultures contradicts it... 

With respect to the OP, hydei can be a problem if you use only the very first emergence you can actually have problems as the hydei have a sexual bias on emergence with is compounded my a lag to reaching maturation. There is a heavy bias for females in the early emergence so if you use that as your starter you may lack males (or only have a few males) and end up with a slow start or non-starting culture. 

There can also be a skewing of the time to egg laying as the flies require several days to reach maturity after they emerge (which is why at about 75 F it takes about 18 days to complete the life cycle. 

And for what it it is worth, if your cultures are started consistently from the first emergence you can select the flies to be intolerant of the conditions post emergence which causes the cultures to crash. 

some comments 

Ed


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## S2G (Jul 5, 2016)

http://www.dendroboard.com/forum/food-feeding/91535-any-tricks-increase-hydei-production.html

I think this has some good info. A quality mite free source and preventative seems to be key as well.


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## Ed (Sep 19, 2004)

S2G said:


> http://www.dendroboard.com/forum/food-feeding/91535-any-tricks-increase-hydei-production.html
> 
> I think this has some good info. A quality mite free source and preventative seems to be key as well.


it depends on the kinds of mites in the culture. In most cases they don't predate on the flies (at any stage) and at best compete for food but generally don't really start to take off until the cultures have started to dry out. At this point, simply managing the mites is sufficient to get great production so a mite free source really isn't needed. 

some comments 

Ed


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## S2G (Jul 5, 2016)

You need the right media. They are a pain to get going and are dirty. It could also be the DNA. Hydei need to be recycled almost every month to every other month to get booms back to where they need to be. So if the media does not have enough anti microbial properties to it the boom will severely be affected. I also noticed with Hydei that the Golden variety seem to produce better, and are more forgiving with not so great medias.

Above is my understanding of hydei.

Using superfly (only media that worked for me with hydei). I like to not use the first batch, and instead use the second. Then make another one about a week later, and use your 2 new staggered cultures to perpetuate. If I have staggered cultures I'll grab from different stages to seed my new ones. Ed is way more knowledgeable so he would be able to help more, but this is what I did.

My personal opinion is kick the hydei to the back burner. I got such inconsistent yields with them depending on time of year, etc. I just gave up. Way too much trouble...again IMO. I switched to mels and turk gliders. They were way less of a hassle and more consistant (turks produced really fast). I also used bean beetles as well. I kept big tincs, leuc's, terribs, and bicolors which they didn't seem to mind. Bigger terribs would sometimes turn their nose up, but hunger won. Since your frogs are not far off I think this would be a way more consistant staple while you figure out hydei on the side so you don't end up short on food. Consistency is key though. I would be replicating my exact schedule which in this case would involve dumping flies you would normally feed. My 2.5c from my experiences


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## serial hobbiest (Mar 5, 2017)

Any info in the Edcyclopedia as to the cause of over-population crashes though? I'm really curious about this.


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## serial hobbiest (Mar 5, 2017)

S2G said:


> Hydei need to be recycled almost every month to every other month to get booms back to where they need to be.



What do you mean by "recycled?"


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## S2G (Jul 5, 2016)

serial hobbiest said:


> What do you mean by "recycled?"


Stronger generation of flies is the way it was explained to me. I'm really not an expert on hydei so I would ask someone who breeds them consistently. That statement was originally from j halter of the old genesis exotics(biodude now or something). The way i mentioned above is what worked best for me, but like I said i switched to turks/mels due to getting fed up with inconsistent production. Late fall and winter I had pretty good results. Spring and summer were a crap shoot (hot & humid weather).


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## Ed (Sep 19, 2004)

S2G said:


> You need the right media.


The same media used for melanogaster works just fine for hydei so I'm not sure where you got the idea that they need a different media. I cultured hydei on my version of the basic Carolina Biological Company mix as well as melanogaster and for awhile I even cocultured the two together for years. 



S2G said:


> get booms back to where they need to be. So if the media does not have enough anti microbial properties to it the boom will severely be affected..


By definition, if there are a lot of antimicrobials in the media then your going to cause problems with the yeasts and that could cause problems but otherwise, your off base somewhat. Setting up new cultures is just like setting them up for melanogaster just need to account for the issues with first emergence sex ratios and time to sexual maturity. This can easily be resolved by using flies from later in the emergence cycle... 



S2G said:


> My personal opinion is kick the hydei to the back burner. I got such inconsistent yields with them depending on time of year, etc. I just gave up. Way too much trouble...again IMO. I switched to mels and turk gliders. They were way less of a hassle and more consistant (turks produced really fast). I also used bean beetles as well


For awhile I stopped culturing hydei simply because I didn't have enough demand to make that culture along with bean beetles so I stopped since that time I've picked them back up due to some non-anurans in my collection. You can easily substitute bean beetles as that sized feeder with very little issues so there isn't a dire need to use hydei for most of the animals that can consume them. 

At this point in time, there are a number of options that weren't really available even 15 years ago.. 

some comments 

Ed


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## Ed (Sep 19, 2004)

serial hobbiest said:


> Any info in the Edcyclopedia as to the cause of over-population crashes though? I'm really curious about this.


See this thread http://www.dendroboard.com/forum/food-feeding/42419-genetics-ff-culturing.html

some comments 

Ed


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## Ed (Sep 19, 2004)

S2G said:


> Stronger generation of flies is the way it was explained to me. .


If this was from an "oldtimer" then it could be part of the information that was circulated for years about keeping cultures from crashing... there were a lot of different ideas for what turned out to be due to selection pressures to deal with mites which in reality aren't the big issue that was once thought. 

I should also note that the claims for cinnamon as a mold inhibitor are greatly exaggerated (see this thread http://www.dendroboard.com/forum/food-feeding/270866-fruit-fly-cultures-crashing.html#post2602050). 

some comments 

Ed


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## serial hobbiest (Mar 5, 2017)

Ed said:


> With respect to the OP, hydei can be a problem if you use only the very first emergence you can actually have problems as the hydei have a sexual bias on emergence which is compounded by a lag to reaching maturation. There is a heavy bias for females in the early emergence so if you use that as your starter you may lack males (or only have a few males) and end up with a slow start or non-starting culture.
> 
> 
> Ed


Re the lagging June 17 culture mentioned in my OP. Last night (July 10) I noticed a small emergence in this culture (like two dozen, perhaps) which surprised me, because I haven't seen a single pupa, but I guess a couple must've been hiding. It's still writhing in maggots, although perhaps a tad inactive, and mostly small. Is this the "lag to reaching maturation" you speak of? Do you suspect I seeded this culture from a first emergence? (I'm note taking now, and won't have such silly questions in the future ).

At this point I'm tempted to add a little extra nutritional yeast to this culture because it's as if the maggots stopped growing, leading me to wonder if the maggot population is so high in there, that they literally ran out of food. Seems plausible to me that if 90% of my seed flies were female, and the few lucky guys in there managed to fertilize all those eggs. 

Thoughts & comments much appreciated.


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## Ed (Sep 19, 2004)

serial hobbiest said:


> Re the lagging June 17 culture mentioned in my OP. Last night (July 10) I noticed a small emergence in this culture (like two dozen, perhaps) which surprised me, because I haven't seen a single pupa, but I guess a couple must've been hiding. It's still writhing in maggots, although perhaps a tad inactive, and mostly small. Is this the "lag to reaching maturation" you speak of? Do you suspect I seeded this culture from a first emergence? (I'm note taking now, and won't have such silly questions in the future ).


It could be due to that effect but there are other possibilities as well, as an example consider that given the longer life cycle that they will consume more media so it doesn't take a huge number of flies to deplete the media. Instead of adding just the yeast, add more media as that is going to stay balanced but it can be difficult to do this well since if you put it over the larvae you can suffocate them. Instead place the media in a second container and then transfer the old culture onto the new media. One of the things people don't realize is that larger maggots will form feeding groups with similar sized larvae and use the group to exclude smaller maggots from better feeding locations. The general description on how the larvae feed is known as a scramble competition or scramble feeding. 

One of the things that can also skew the emergence of adults in Drosophila cultures is that the larvae can predate on larva looking for a pupation sites if there is a perception of low food availability. This can skew the size of the maggots both through competition and the elimination of larger magggots. 

see https://www.nature.com/articles/ncomms2744

Vijendravarma, Roshan K., Sunitha Narasimha, and Tadeusz J. Kawecki. "Predatory cannibalism in Drosophila melanogaster larvae." Nature communications 4 (2013): 1789.

some comments 

Ed


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## Pumilo (Sep 4, 2010)

Serial hobbiest, in another recent thread, I'm pretty sure it was you who posted a fruit fly media recipe quite different from, well, pretty much every other recipe I've ever run across, and I've seen more than a few.
Was that you with the recipe that has no, sugar, molasses, fruit, malts, corn syrup, or any other type of sugar?

My first thought is to put them on a tried and true recipe, before looking for other problems. I think there is a reason for the sugar. I've heard that the melonogaster fly is the most genetically manipulated organism on the planet. Whether that's true or not, you can't argue that flies have been bred in laboratories for many years, by many different scientists. Scientists use a sugar source. Do a search for the book "Drosophila", by Therese Markow and Patrick O'Grady. It shouldn't take too much digging to find some of the recipes posted in there. "Drosophila" may not be a common book in our hobby, but if you are a scientist working with flies, you've read it. There are many different recipes, but one thing remains consistent. They all have some sort of sugar. 

Ed, I would love to hear your thoughts on dropping the sugar from the recipe.


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## S2G (Jul 5, 2016)

Ed said:


> The same media used for melanogaster works just fine for hydei so I'm not sure where you got the idea that they need a different media. I cultured hydei on my version of the basic Carolina Biological Company mix as well as melanogaster and for awhile I even cocultured the two together for years.
> 
> some comments
> 
> Ed


That quote was originally from J Halter on another board several yrs back. What I posted was my original understanding and what worked for me. I'm far from an expert though and was hoping you would provide some better insight...which you did.


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## serial hobbiest (Mar 5, 2017)

Pumilo said:


> Serial hobbiest, in another recent thread, I'm pretty sure it was you who posted a fruit fly media recipe quite different from, well, pretty much every other recipe I've ever run across, and I've seen more than a few.
> Was that you with the recipe that has no, sugar, molasses, fruit, malts, corn syrup, or any other type of sugar?
> 
> My first thought is to put them on a tried and true recipe, before looking for other problems. I think there is a reason for the sugar. I've heard that the melonogaster fly is the most genetically manipulated organism on the planet. Whether that's true or not, you can't argue that flies have been bred in laboratories for many years, by many different scientists. Scientists use a sugar source. Do a search for the book "Drosophila", by Therese Markow and Patrick O'Grady. It shouldn't take too much digging to find some of the recipes posted in there. "Drosophila" may not be a common book in our hobby, but if you are a scientist working with flies, you've read it. There are many different recipes, but one thing remains consistent. They all have some sort of sugar.
> ...


That's right, there's no sugar in the recipe I use. I got the recipe from a YouTube channel called Aquarimax, which seems to cover a broad range of herpeculture topics, especially the how tos of breeding pretty much all your feeder insects for whatever animals. After browsing several videos & homemade fly mixes, I decided on his (after a little back & forth in the comments section) because it seems to make sense. What's the sugar for? To feed the flies, or the yeast, or both?

"Why did I settle on that recipe?" you may ask... Well... in a nutshell, we want to grow flies, not produce CO2 & alcohol (which is non conducive to life in general, albeit that fruit flies are probably quite tolerant of it, given their nature). His recipe looked to me the most sure way to avoid fermentation. No active yeast, and no added sugar. 

Borrowing what knowledge of yeast I have from brewing beer, I can at least be fairly certain we don't want _active_ brewers yeast (Saccharomyces sp.) in our fly cultures, given its rapid reproduction rate (yeast consumes oxygen in the process- I'm pretty sure maggots have a use for that) and how aggressively they ferment, which is an anaerobic process. But I get it. We need to feed flies Saccharomyces because of its high nutritional value... So we use "dead" Saccharomyces in the mix.

It may be of interest to note that the wild yeasts (Brettanomyces sp.) that readily grow on the skins of fruit (what wild fruit flies eat) are a fair bit slower in reproduction, and dead slow in fermentation (Yes, I have a couple batches of "wild" beers (lambics) under my belt, and were very successful, thank you ). For comparison, a typical 5% abv ale will ferment out in about 2 weeks compared to months (sometimes more than a year) for a Brettanomyces brew. It may also be of interest, that unlike Saccharomyces, Brettanomyces is capable of breaking down huge, complex sugars and even starch into fermentable forms. Why am I going here? Well, perhaps it is the case, that the flies themselves are inoculating our cultures with Brettanomyces. We don't sanitize the flies, so it stands to reason. The "Adam & Eve" flies no doubt brought this with them into the initial culture. And since Brettanomyces can break down starch, maybe there's no real need for sugar. Also in the instructional video, the guy mentioned he _occasionally_ adds a pinch of bakers yeast. (To date, I haven't tried this- I don't see the point... well, maybe I'm starting to). I drilled him about that, and he basically told me that it's insurance that there's at least _some_ yeast activity in the cultures, which ensures the flies will transfer some to the next. I know nothing about bakers yeast reproduction & fermentation unfortunately, but this practice of ensuring some active yeast has got me thinking... perhaps not doing this is part of my problem. This is a good time to mention that this morning after my previous post, I went ahead and dumped in another tablespoon of nutritional yeast to that Jun 17 culture. Most of it didn't even hit the media- it got stuck to the glass and all over the soggy excelsior. When I got home from work, I suddenly have all these maggots finally crawling up the glass, and there's no trace of nutritional yeast left- evidence that they ran out of food, right?! Perhaps if I had added some active yeast to that culture when I made it, it could have reproduced enough that this "stuck" culture wouldn't have occurred in the first place. Perhaps if I had added Brettanomyces, the results would be even better given that they'd be happily munching on the potato starch!

Anyhow, now you see where my head is at. Thanks for the book recommendation. I'll look into the whys of using sugar, as my wall of text is no doubt a huge misconception.


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## Ed (Sep 19, 2004)

Working backwards... so I may not need to address all posts... 



serial hobbiest said:


> What's the sugar for? To feed the flies, or the yeast, or both?


Or it could be for a third reason... it would change the osmolality of the culture reducing the number of undesirable microbes that would like to grow in the culture.... but it is likely to be more than one and one of the other reasons is to be to increase the biomass of the yeast rapidly as this was found in early studies to reduce the time to development... see Sang, James H. "The quantitative nutritional requirements of Drosophila melanogaster." Journal of Experimental Biology 33.1 (1956): 45-72.

Additionally, glucose is required to metabolize food reserves stored during the prepupal stage see Hollingsworth, M. J., and Judith V. Burcombe. "The nutritional requirements for longevity in Drosophila." Journal of insect physiology 16.6 (1970): 1017-1025.

As a personal opinion, I would not stop including the sugar... but that is just an opinion. 



serial hobbiest said:


> "Why did I settle on that recipe?" you may ask... Well... in a nutshell, we want to grow flies, not produce CO2 & alcohol (which is non conducive to life in general, albeit that fruit flies are probably quite tolerant of it, given their nature). His recipe looked to me the most sure way to avoid fermentation. No active yeast, and no added sugar.


Everyone keeps gravitating to the alcohol idea in the cultures but people keep ignoring that unless your mixing the live yeasts deep into the culture, most of the metabolism by the yeast isn't going to produce alcohol but water and CO2 as it is mainly aerobic respiration. The larva by their constant movements churn the upper levels of the media introducing oxygen to the media. 



serial hobbiest said:


> Borrowing what knowledge of yeast I have from brewing beer, I can at least be fairly certain we don't want _active_ brewers yeast (Saccharomyces sp.) in our fly cultures, given its rapid reproduction rate (yeast consumes oxygen in the process- I'm pretty sure maggots have a use for that) and how aggressively they ferment, which is an anaerobic process. But I get it. We need to feed flies Saccharomyces because of its high nutritional value... So we use "dead" Saccharomyces in the mix.


Actually you want both in an ideal mix.. but your going to get some regardless if you add it as well or not... the adults will transfer it with them both in their GI tract and on their bodies but the larvae do grow better on live yeast (see above citations). The addition of live baking yeast strains at the start of a culture has a twofold usage, the first is to ensure that there is greater competition against unwanted microbes and to encourage rapid egg deposition. Early emergence of the larvae also discourages other organisms from colonizing the media particularly fungi that can cause issues with the flies. The usage of the inactivated yeasts is to supply an additional protein source that is readily available as low protein levels reduce the rate of growth...

see Becher, Paul G., et al. "Yeast, not fruit volatiles mediate Drosophila melanogaster attraction, oviposition and development." Functional Ecology 26.4 (2012): 822-828.




serial hobbiest said:


> It may be of interest to note that the wild yeasts (Brettanomyces sp.) that readily grow on the skins of fruit (what wild fruit flies eat) are a fair bit slower in reproduction,


If you think that the wild flies are looking for Brettanomyces then your incorrect. That group of yeasts are very rarely found in the gut of the wild flies or as a preferred yeast food. Instead they utilize much more rapidly growing yeasts (keep in mind that fruits are low protein sources so they want a rapid conversion of sugars to proteins to ensure that the maggots complete the development before the ephemeral food source is gone... 

see for example Chandler, James Angus, Jonathan A. Eisen, and Artyom Kopp. "Yeast communities of diverse Drosophila species: comparison of two symbiont groups in the same hosts." Applied and environmental microbiology 78.20 (2012): 7327-7336.

and while uncommon, Saccharomyces are known to be found in wild Drosophila... 




serial hobbiest said:


> Saccharomyces Saccharomyces, Brettanomyces is capable of breaking down huge, complex sugars and even starch into fermentable forms.


This might have been an issue if the fact that the maggots actively excrete digestive enzymes for a wide range of materials to ensure that the yeast has access to the nutrients it needs... see for example Gregg, T. G., et al. "Insectivory and social digestion inDrosophila." Biochemical genetics 28.3-4 (1990): 197-207. (and it ignores that Brettanomyces aren't really of interest to the flies). 



serial hobbiest said:


> Why am I going here? Well, perhaps it is the case, that the flies themselves are inoculating our cultures with Brettanomyces. We don't sanitize the flies, so it stands to reason.


I find this idea puzzling... given that for more than 50 years, Saccharomyces cerevisiae has been the yeast added to the cultures of the flies as a food and a competitor for other microbes. Given the disparate rates of growth of the two, why would you think that the slower growing microbes would still be present and not outcompeted over the previous decades? 

some comments 

Ed


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## Ed (Sep 19, 2004)

S2G said:


> That quote was originally from J Halter on another board several yrs back. What I posted was my original understanding and what worked for me. I'm far from an expert though and was hoping you would provide some better insight...which you did.


It was a puzzle to me and outside of the original comments at some IAD's I've never found the origin for that assertion. No worries otherwise, I'm always trying to run down things to see where they originated. 

some comments 

Ed


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## serial hobbiest (Mar 5, 2017)

Ed said:


> I find this idea puzzling... given that for more than 50 years, Saccharomyces cerevisiae has been the yeast added to the cultures of the flies as a food and a competitor for other microbes. Given the disparate rates of growth of the two, why would you think that the slower growing microbes would still be present and not outcompeted over the previous decades?
> 
> some comments
> 
> Ed


I considered it as a possibility, especially when not knowing the history of fly culturing, or the history of the line of flies I currently have in particular, that's all. I also figured the wild yeasts' ability to utilize the starches and complex sugars that brewers yeast cannot would allow it to hang in there. But it makes sense that the maggots are doing that breakdown anyhow...

Thanks for addressing all my nonsense, Ed 
I told Doug I owe him a steak dinner, but to be fair, I'll have to cough up one for you too.

Seriously, thanks for all your help you guys.

-Jason


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## Ed (Sep 19, 2004)

serial hobbiest said:


> I considered it as a possibility, especially when not knowing the history of fly culturing, or the history of the line of flies


People are often surprised to discover that some Drosophila have been in culture for over 100 years... and hydei was known as a distinct species as long ago as 1891. 



serial hobbiest said:


> Thanks for addressing all my nonsense, Ed


Not nonsense, you just didn't check your assumptions before following the logic chain down the rabbit hole.  



serial hobbiest said:


> I told Doug I owe him a steak dinner, but to be fair, I'll have to cough up one for you too.


We're cool ... its not a big deal. 

some comments 

Ed


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