kova
Warning, Warning!00
If you have a favorite fruit fly mix that you are very happy with, do not read this! It will only upset you.
Most folks have no idea about what fruit fly larvae eat, but since the larvae will eat just about any kind of fermenting food in nature, everyone is happy with their results.
Potato flakes provide an excellent food source, not for the maggots, but for the bacteria and yeast cells that the maggots eat. Potato broth is a standard culture medium and potato flakes are cheap.
Yeast will grow in the medium whether you put any in there or not, since wild yeast spores are in the air. But we grow massive numbers of maggots in a very small area, so we need to supplement the supply.
The habit of sprinkling yeast on the top of the mixture comes, I think, from the fact that people have read that yeast is necessary, stirred it in and seen the massive production of carbon dioxide. The wife of former member Arkanas, poured in a whole packet on her first try, years ago, with dramatic results. I routinely use more than that. Yeast needs food in order to grow, so you must add sugar.
These three components with water added (and the maggots don't care if it is spring , distilled or tap water, though some seem to prefer Evian) are sufficient to raise FF larvae.
The yeast can be inexpensively supplemented with brewer's yeast. This consists of yeast spores that were broken open in the brewing process leaving the amino acids (protein precursors) in an edible form.
Rebecca and i have both experimented with the addition of animal protein in the form of milk whey or casein. It has been found, in a Danish paper that was discussed here a while back, that it has a positive tritrophic effect on spiderlings (and we can assume, mantids), and produces amazingly high yields of flies. the problem that I have had with it, though, is that in one batch of a dozen pots, some will have huge yields and some will start to grow anaerobic bacteria, so I have reduced the amount to where it may not be very significant.
There is no need to use vinegar or booze. They certainly attract the flies, but their mold inhibiting value is small and there is no need of an ovipositing stimulus once the yeast/sugar mix has become moist.
It's value as a mold inhibitor is modest at best as demonstrated by the fact that no academic or commercial fly lab uses it. A pound of Paraben from Josh's Frogs will last a very long time indeed, and Rebecca uses a similar, apparently cheaper item (sorry, love, I forgot its name!) available in the supermarket baking goods isle..
Paraben is used at a strength of 1tsp (5ccs) to 21/2 cups of mixed dry food. I didn't realize, until a few years back, while reading Comsumer's Reports, how hard it is to mix this evenly through the food in a stand mixer. Using a spot of food dye and waiting to see when it was evenly distributed, they came up with 15+ minutes for many common mixers, so put it in the mixer and forget about it for a while.
People who talk about "gut loading" their prey insects seem to have no idea of the difference between it and "feeding' and often use the terms interchangeably and wrongly. Gut loading is a method by which the gut of a prey insect like a cricket is filled with a mixture of vegetable matter and vitamins and trace elements that the predator may get in its usual diet. It was introduced as a means of providing these nutritional elements to reptiles and amphibians that swallow their prey whole. It does not apply to the feeding of insects and it certainly does not apply to carbohydrates such as honey, which are often well on their way to being absorbed by the fly before it is eaten. Tritrophic benefits seem to apply exclusively (and I would like to be corrected if i am wrong on this,) to animal (fly thigh) and plant (pollen) protein.
OK. I know that the vast majority of us is going to ignore this and continue to talk about "gut loading" and "masa flour" and apple slices and vinegar, but until the next time, it made me feel better, and that is always a Good Thing.
