A Definite Must Read for Any Black Soldier Fly Enthusiasts - Discussion of Larval Taxonomy

Good news.... bad news... or is it bad news first? I think I will start with the bad news- I am not sure you can locate this paper; however, the good news.... this study was the first life-history study of the BSF. In fact, I believe this paper might be the ONLY one to examine and describe the different larval stages and provide physical features that allow you to distinguish them.

May, B. M. 1961. The occurrence in New Zealand and the life-history of the soldier fly Hermetia illucens (L.) (Diptera: Stratiomyidae). New Zealand Journal of Science 4: 55-65.
Adult BSF: The paper discusses a single feature for distinguishing male and female adult BSF. The author concludes that coloration patterns on the abdomen are diagnostic of males and females (not sure I feel the same).

​May (the author) indicates the translucent sites on the anterior portion of the abdomen are narrower on males than on females. Of course- I think we all recognize the easiest feature is the terminal segment of the abdomen- where the genitalia are located. Males have a heavy sclerotized (appears to look like a crown with four heavily darkened points) genitalia, while females have two fine "hairs" protruding from the abdomen.  There are also antenatal differences as well. I will have to dig up that fact so I can share with you later.

Larval Development: While the first life-history study on this species is important- I think the more critical information in this publication is with regards to identifying the instars (stages). The differences were determined by head capsule width. Basically, as the insect passes through a stadia, the head capsule expands to a larger size. I might be mistaken- but I believe this is the first paper to apply the term prepupa to the BSF (last instar). Of course- if someone locates an older reference, please share as we all want to learn (and be correct).

​One thing to note about BSF larvae- they start out extremely small (0.01 mg) but can grow to be up to 0.5 g (yes- gram). So understanding these stages and how they can vary is critical for understanding if adults are laying eggs in your compost or your facility and and when- knowing such information can be critical for colony maintenance and mass production as you want to prevent different stages growing together. When this happens- harvesting larvae can be a challenge as well as maximizing weight gain of the larvae.

Why is this information important? Well, I believe if we ever want to get to the level of understanding as to when larvae accumulate fat and protein, operating under this framework will be critical. I highly encourage anyone examining the development of this species to consider these six instars as focal points of measurement. How this insect develops, accrues fat and protein, and resulting behavior as related to these instars could be critical for developing highly refined processes for mass production.  

At minimum- it is always good to pay homage to those that cam before us- especially if you consider how outstanding their research efforts were.

Author

Jeff Tomberlin, PhD, BSF History Sleuth
Twitter: @FliesFacility
Director, EVO Conversion Systems
evoconsys.com