Biology of the Black Soldier Fly, Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae) in Jaffna, Sri Lanka
Abirami Sivanantharaja, R Gnaneswaran
The Black soldier fly is known worldwide for its role in decomposing organic waste matters. However less effort has been done so far in studying its complete biology. Adult insects lived on an average of 12-13 days under optimal conditions (31ºC and RH 80%) with lifespan decreasing to 6 days as RH goes down to 60%. Larva were observed to have a lifespan of 20.0 ± 1.05 days until they became Pre-pupa at the temperature 30.15 +- 0.26ºC. Larva were observed to have prolonged lifespan during the rainy season from October to January when the temperature went down to 28ºC. Adults were observed to lay their eggs even in the absence of decomposing wastes and eggs were collected from various places such as sponges, cardboards, and in the meshes of the nets used for caging. The egg count was found to be 477 ± 10.69 eggs per batch. When the environmental temperature was 30.15 +- 0.26ºC, eggs hatched in 4.5 days. The length of the freshly laid eggs was 0.901 ± 0.013 mm. Time taken for the adults to emerge from their pupal stage was 14.7 ± 1.07 days at 30.15 +- 0.26ºC. Total lifespan from egg to adults was found to be 57.8 days at 30.15 +- 0.26ºC. By using Dyar’s law it was found that the larvae of BSF undergo five distinct morphological stages (Instars) during their larval period. The Black soldier fly larvae were found to have a strong positive olfactory reception to decomposed organic wastes than other food sources. The average length of the first, second, third, fourth and fifth instar lava were 2.35 ± 0.02, 6.45 ± 0.07, 10.26 ± 0.11, 15.92 ± 0.23 and 17.34 ± 0.09 mm. Mean length of the adult fly was 16.92 ± 0.21 mm, Mean wingspan of adult male was 12.25 ± 0.21 mm and of female was 13.02 ± 0.23 mm.