I've had a fairly good number of BSF coming to my bait boxes for the last 10 days and I've noticed some trends. House flies show up as soon as it's light out, but BSF don't arrive until close to noon. Two days ago it was hot and sunny and there was a constant BSF presence in my container. Throughout the afternoon I could find them laying eggs at any time, and usually there were 3 or 4 of them laying simultaneously. Yesterday was overcast almost all day, and there where the usual number of house flies but almost no BSF. I think I only saw one or two. This may be important because it's advised to keep your BSF container in the shade, but the adult BSF seem to prefer a sunny location to lay. The hardest part of raising BSFL is getting the colony started so I plan on putting more time into working on these types of details.
Once the BSFL are established other fly species will be repelled by an info-chemical which the BSFL produce. In the start up phase you may get house fly larvae in your container or BioPod, but it isn't really a problem. I've actually been collecting the (smaller) house fly larvae and feeding them to my Fathead minnows. I'm a little more cautious about sanitation at this point too, because with house flies coming into the container there is much more of a concern about pathogens.
