The most common cause of BSF larvae dying is overheating and the common wisdom is that 113ºF causes instant death. A recent study by Dr. Tomberlin indicates that high temps during the early stages can effect development and also the survival rate significantly. I haven't had the time to thoughtfully read the study but the link is below. When I skimmed the article I noticed something unexpected; the temps are much lower than what I normally think about harming BSF. I believe a controlled temperature of 97ºF caused almost all of the larvae in that group to die early. Obviously BSF are surviving in climates that get hotter than that. I assume the temperatures in the study were constant and my current theory is that an average temperature of 97º is harmful, but that BSF can manage higher daytime temps when the nighttime temps lower the average.
The study also seems to give some evidence about why some larvae and adults are much smaller than others.
