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.

My First Attempt to Attract Black Soldier Flies – May 2007

May 242008
 


As soon as I realized that black soldier flies were present around my home I put some food scraps into a bucket with a lid and cut a few small holes into the sides.

my first bucket of black soldier fly bait

BSF will crawl through a small opening to access a food source for their eggs. They don’t eat in their winged stage which is referred to as the adult stage. In fact, they don’t even have fully functional mouths because they only live a few days, just long enough to mate and lay their eggs.

I initially put out dog food, cottage cheese, bread, and assorted fruits and vegetables. Note: You can and probably will also attract ants (and most importantly, dogs) with this type of mixture so do what you can to keep these undesirable animals out of the bait. Within a few hours I had a few ladies (female BSF) checking out the offering and depositing eggs.

black soldier fly laying eggs on cardboard


If you look at the left side of the bucket in this next image you can see a BSF just before it entered the bucket through the small hole.

black soldier flies entering bait bucket

Be sure to keep the container with your food scraps out of the direct sunlight or you may overheat the larvae. If this happens they will evacuate the container if possible and if not they may die. I learned this the hard way.

An established and properly balanced container of Black Soldier Fly larvae will not have a bad odor. BSFL will consume the food scraps so quickly that it doesn’t have time to develop the bacteria that causes bad odors. If you overload the colony with food it can begin to smell before it’s eaten. A two foot diameter (60 cm) BioPod can process several pounds of food scraps each day.

Boy Meets Girl (fly) – my first encounter with a Black Soldier Fly

May 242008
 

possible-black-soldier-fly-wtrmk2

In May of 2007 I was sitting at the computer in my home office researching black soldier flies. I had not yet seen one at that point in time, at least not that I was aware of. It was a warm south Georgia spring day and I had left the door open. A few bugs flew in and out, but it was just too nice to close the door. One bug in particular was rather loud as it buzzed at the window apparently looking for a way out. I’m in the habit of photographing insects that I find around the house so I snapped a pic of this bug. I went back to my research and entered “black soldier fly” into Google and clicked “search images”. As you’ve probably figured out already the “bug” that had entered my office and buzzed my head as I did the search was a black soldier fly (Hermetia illucens). Black soldier flies rarely enter houses and in the year that I’ve worked with them since there has been only one other time that a BSF entered my office. The photo above is the BSF from that day, the first that I had seen. And, yes, I should clean the windows more often…

One of the best ways to identify a Black Soldier Fly is to observe the white legs, or tarsi.