Black solidier fly larvae-variation in growth rate

Sep 242008
 

I recently collected a newly laid clutch of black soldier fly (Hermetia illucens)eggs for a photographic study of their development and I isolated three of them for the photos. I placed the three individuals and the remaining few hundred BSF from that clutch into identical containers. I didn’t keep detailed records, but there is an interesting comparison that I believe illustrates the flexibility of BSF development.

larval-growth-variance-w

Temperature and humidity were approximately the same for both batches of larvae. The large larvae is one of the three that was separated for the photos and all three are similar in size. The small larvae is from the more crowded container which held the bulk of the larvae. The same type of food was available to both groups, but I can’t attest to the quality of the food in the more crowded environment that produced the smaller larvae. From casual observation it appeared that there was always food available to both groups. The most obvious difference between the two containers was the density of larvae. The small larvae where moved into a larger container six days after hatching and seem to be healthy and growing, but are still relatively small.

I imagine any properly educated researcher would not be surprised by this difference in development, but to this layman it’s very interesting.

solider

Trial and Error – Starting My First BSF Colony

May 242008
 

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:

bsf eggs on cabbage

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.

first batch of black soldier fly larvae

black soldier fly larva and a penny

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.