I put out my first bucket of food scraps to attract black soldier flies in the spring of 2007. I soon observed the adult flies laying eggs in my bucket so I assumed that in a few days I would see larvae.
The literature I’ve read states that BSF eggs will hatch in roughly 100 hours.
After six days of seeing BSF in my bucket I had observed what I correctly assumed were BSF eggs, but still no larvae. The evenings had been cool and I imagined that temperature was the limiting factor. I took this photo on the sixth day and you can see a group (clutch?) of eggs which are about 1/2 inch (12 mm) across:
More than two weeks after observing BSF all I had to show was a few fruit flies and some dehydrated food scraps. I wasn’t even seeing BSF anymore. At that point I began to lose interest in the project and I stopped checking the bucket on a daily basis. We were experiencing drought conditions then and the last time I had checked the bucket I didn’t even replace the lid. We finally got a good rain but since I had lost interest I didn’t bother checking the bucket. A few days after the rain I passed by the bucket and noticed some flies buzzing around. I took a closer look and saw that they were black soldier flies. I looked inside the bucket to see some sloppy food scraps, and finally, BSF larvae.
The fact that some of the larvae were almost full size seems to indicate that they had hatched even before the rain. Maybe the dry conditions didn’t stop the development of the eggs but instead just slowed it down and possibly limited the number of survivors. I think it may be best to keep the food scraps shaded and moist to help the eggs develop. Also, when the larvae first hatch they’re very small and it won’t be easy to see them for several days.