After working with both species for a couple weeks, I can tell you that there’s really comparison between the two. BSFL do EXPONENTIALLY more damage to rotting food than YSFL could ever hope to do. Also, it seems that YSF do not lay anywhere near as many eggs, and thus its much harder to get enough grubs at any one time to actually break down food in any meaningful way. Another interesting observation, the YSF totally ignore cardboard strips, so I’m assuming that they either lay their eggs on the side of the container or directly onto the food. Also, they are not afraid to land directly on the food, unlike BSF, and are thus probably more likely to spread germs. Also, YSFL do not self-harvest. They try to find a drier spot within the container and pupate there. Finally, BSF pupae are 4-6 times bigger than the biggest YSF pupae.

I finally broke down and purchased BSFL larvae off the internet a little over a week ago. In that time, some of the mature larvae (pupae) have hatched, bred, mated, and laid thousands of eggs (which have not hatched yet).

Conversely, my YSF have hatched, bred, and laid maybe 100 eggs which did hatch and have done nowhere near the damage that 10 BSFL can do in one night.

Bottom Line: the only reason that I can think of that you would want to actively propagate YSF is if you need a high protein feeder for a very small pet, such as baby tilapia, baby geckos, etc.

I haven’t checked my observations against any other sources or studies… just my observations. So to your point Mike, there could be some external factors that I’m not accounting for that are unfavorable to the YSFL. However, considering that they are the indigenous species, I would expect them to outperform the species that I had to fly in.

Last observation: the YSFL REALLY like dog feces (probably why they exist in my area in the first place). They are not as enticed by coffee, bread, or meat. They do, however like corn and high sugar content foods such as rotting grapes. BSFL don’t seem to really care what you feed them. They annihilated about 10 gallons (sorry, container measurements) of coffee grounds in about 2 days.

Conclusion: even if you have to purchase a few BSFL off the internet in order to jump start a local population [I live downtown, so that was very necessary for me], I would absolute do that over trying to compost with YSF. Just my $.02, hope that’s helpful.

There’s a bit of information on YSF here and here.

My initial impression is that they’re so much smaller than BSFL, that they couldn’t possibly be as good for composting. Also, they seem to go from larvae to pupae VERY quickly. So, I doubt they’ll eat anywhere near as much. However, I’m wondering if I can get enough numbers of them… maybe they can still do some damage to food scraps?

I will certainly update you guys with anything I learn.

P.S. Thanks to everybody for all the information I’ve gotten from this site sneaking around reading things like a creeper!

Mike

I can see having a worm bin indoors and a BSF bin outdoors so the female doesn’t repopulate the worm bin. Would that work??

I’m seeing quite a few requests for methods of removing them from worms bins. AFAIK there is not a sure fire method to do this. Also BSF are likely to repopulate the bin anyways as the gravid female BSF find the conditions in worm bins ideal for laying their eggs as there is a ready supply of food for the larvae when they hatch.