Introduction The growing population demand increase in the need for animal proteins. Global food consumption trends, lifestyle modifications, and changes in food preferences are all impacted by population expansion. Animal protein for human consumption is produced rather quickly in the poultry industry, which is a subset of livestock farming. Protein concentrate with high biological values is required due to the intensifying production of poultry (Hossain and Blair, 2007). As insects contain significant nutrients and chemicals that regulate animal microbiota and improve animal health, they are one of the most attractive prospective sources of chicken feed. The fact that hens in the conventional poultry production method scavenge all edible items from their environment, including insects, suggests that insects are the poultry's natural source of food. Black Soldier Fly - an introduction The Black Soldier Fly (BSF) (Scientific name : Hermetia illucens), is a non-pest fly belonging to the family Stratiomyidae. It is one of the insect species that has great potential for extensive industrial production. Black soldier fly larvae are packed with essential nutrients, including 40- 45% protein content, along with fats, amino acids, and other vital nutrients. These larvae feed on a variety of organic wastes which make them a sustainable protein source. After processing, the larvae are converted into a defatted meal that can be easily integrated into feed formulations. This feed offers a balanced diet supporting the growth and health of livestock and aquaculture. The use of BSF larvae meal has hence rich potential as a substitute for protein source in poultry feeding. Lifecycle of Black soldier fly The life cycle of the BSF could be completed in 23-25 days depending upon the substrate in which the culture was reared and prevailing weather conditions. In its life cycle, the BSF goes through five stages: egg, larvae, prepupae, pupae, and adult. Adult fly mate during flight and seeks for decaying substrates for oviposition. It lays about 200-300 eggs in the decomposing substrate in group and hatches in 2-7 days. Under ideal conditions of between 20°C and 30°C, eggs are typically creamy yellow in colour and take 4 days to incubate and hatch (Newton 2015). Due of their photophobia, BSF larvae appear dull and pale right after hatching (Newton, 2015). They also strive to hide from light. Larvae can grow quickly and eat organic substances with a voracious appetite. The majority of the larvae's life is spent feeding on food and manure wastes, which they quickly convert into calcium, protein, and fat. The larvae start feeding upon the decaying organic matter and pass through six larval instars. The mature sixth instar larvae enter into pupation. The adult emerges in 4-5 days. Two days after leaving the pupal stage, adults are able to move around and reproduce (Myers et al., 2008). Two days after copulation, the female oviposits into dry cracks and crevices close to the larval habitat (Newton et al. 2005). Since adult fly mating levels were shown to be maximum in the presence of natural sunshine, a temperature range of 25°C–35°C and ambient light play a crucial role in the initiation of mating for adult flies (Newton, 2015).The adults don't eat, although they do sip water or other liquids if they are accessible, and they live off the lipids they accumulated as larvae (Newton, 2015). Black soldier flies prefer temperatures between 27 to 330C for effective feed utilisation (Alvarez, 2012). Lower temperatures are probably tolerable since the larvae's feeding action and metabolism produce some heat, allowing them to grow in colder regions (Newton, 2015). The physiological characteristics of the BSF prevent it from having any attraction to dwellings, which reduces any pest-like behaviour and allows it to live its life far from people (Barry, 2004). Apart from having a desirable (soluble) protein content, insect species also contain high amounts of chitin, which is the main constituent in the insect exoskeleton. Chitin is a non-toxic, biodegradable linear polymer. Studies confirm that chitin has effects on innate and adaptive immune response, including the ability to recruit and activate innate immune cells and induce cytokine and chemokine production via a variety of cell surface receptors including macrophage mannose receptor, toll-like receptor 2 (TLR-2), and Dectin-1(Lee et al., 2008). Nutritional importance of Black Soldier Fly Larvae Several publications have reported on the nutritional characteristics of BSF larvae used as animal feed sources. Fresh larvae have a higher Dry Matter (DM) content (35–45%) than other fresh by-products, making them simpler and less expensive to dehydrate (Newton et al., 2008). According to Maurer et al. (2016), dried full-fat BSF larval meal comprised 41.5% Crude protein (CP), 26.5% EE, 4.3% ash, 0.80% Ca, 0.50% P, 0.08% Na, and 0.33% chloride, whereas dry partly-defatted BSF larvae meal contained 59.0% CP, 11.0% EE, 5.0% ash, 0.98% Ca, 0.63% P, 0.08% Na, and 0.28% chloride. According to the findings, full-fat BSF larvae have lower CP, ash, Ca, and P levels than partially defatted ones. When raised on poultry manure, protein levels were reported to be 42.1%, according to Newton et al (Newton et al., 1977). The amino acid profile of the BSF larva is superior to or equivalent to that of soybean meal (SBM) (Tran et al., 2015). According to Ravindran et al. (1999), the lysine and methionine level of the proteins found in BSF larvae is comparable to that of meat feed. According to Cullere et al. (2016), defatted BSF larvae diet had higher concentrations of alanine and glutamic acid than it did of the essential amino acids valine and leucine. The highest level of amino acid content was mostly expressed in the early stages of larval development before gradually declining. The amino acid content of BSF fluctuates during their lifecycle and appears to be related to their CP content. Generally speaking , the CP of black soldier fly larvae meal is lower than that of fish meal but equivalent to other insect meals and soybean meal. Calcium and phosphorus are abundant in the BSF larva (Newton et al., 2005). Depending on their meal substrate, different samples of BSF pre-pupae had varying ash contents. Effect on broilers Various researchers assessed the performance of broilers given BSF larvae diets. Oluokun (2000) compared the production of broilers using BSF larvae, Soybean Meal (SBM), and Fish meal (FM). The author proposed that FM may be upgraded by using BSF maggot meal. The BSF larvae meal has similar nutritional value of SBM in broiler diets without having a negative impact on feed intake, body weight (BW) gain, or feed conversion ratio (FCR). A similar BW increase was achieved when dried BSF larvae were fed in place of SBM, but less feed was consumed, indicating a better FCR (Makkar et al., 2014). According to Cousins (1985), broilers fed a beginning diet based on BSF had daily gains and body weight that were roughly comparable to those fed a fish meal control diet at 10 days old (24.6 vs. 24.5 g/day, 286 vs. 285 g, respectively). These findings were in line with other research (Cullere et al., 2016) that found no changes in daily increase or ultimate weight throughout the grower phase in broiler quails fed either a control diet or a diet with BSF larvae meal. According to Dabbou et al. (2018), grill chicken meals containing BSF increased body weight and average daily gain during starting growth periods, but average daily gain decreased. Gain reduced linearly during the finisher stage, which may be related to dietary BSF larvae meal's detrimental effects on gut morphology when administered at a high dosage (10%). Effect on Layers In small groups of laying hens, Maurer et al. (2016) conducted a feeding study using a partially defatted diet of dried BSF larvae. 12 and 24% of the meals in the experimental diets replaced 50 or 100% of the soybean cake in the control diet, respectively. There were no discernible changes between feeding groups in terms of egg production, feed intake, egg weight, or feed efficiency after three weeks of the trial. While there was no difference in the weights of the yolk or shell, there was a tendency (P=0.05) for reduced albumen weight in the 24% meal group. Additionally, there were no deaths or indications of health issues. With increasing meal portions in the diet, the DM of the faeces rose. There was a significant difference between the 24% meal and control groups (P=0.05). The 12% and 24% meal groups both showed an increase in black faecal pads. There was cause to believe that the meal portion of this diet was too high based on the higher DM of faeces and the bigger proportion of dark, hard faecal pads (24%). Uncertainties remain regarding the reasons behind these variations. Van Schoor (2017) investigated how BSF pre-pupae meal affected the parameters of layer production and the quality of the eggs. Results were likewise encouraging in egg production. The DM of the faeces increased when meal quantities increased in the diet. Between the 24% meal and control groups, there was a significant difference (P=0.05). There was an increase in black faecal pads in both the 12% and 24% meal groups. Based on the increased DM of faeces and the higher proportion of dark, hard faecal pads (24%) there was reason to suspect that the meal component of this diet was too high. Concerning the causes of these variances, questions still linger. According to Mwaniki et al. (2018), feeding 7.5% defatted BSF larval meal to laying hens from weeks 19 to 27 of age resulted in considerably higher body weight than other groups. The condition of the feathers of laying hens with intact beaks was similarly improved by the provision of BSF larvae (Star et al., 2020). Overall, it can be inferred from the results above from various studeis that BSF larvae meal is a potential substitute for FM or SBM in the diets of broilers and laying hens without having a negative impact on performance. Conclusion Based on the thorough research results from several studies, it is possible to draw the firm conclusion that BSF larvae meals are a reliable, affordable, and highly nutritious alternative source of animal protein feed. It might be used as a supplement or as a cheaper alternative to costly traditional protein source diets. In contrast to conventional fish and soybean meals, which are reportedly very expensive and unaffordable for poultry producers, BSF larvae are said to contain 35-42% CP, are rich in minerals and fat, have an improved or comparable amino acid profile, and have an efficient food conversion factor. The majority of study findings supported the viability of completely or partially substituting BSF larvae or prepupae diet for FM. On the growth performances and egg quality of chickens given BSF larvae feed, no adverse impacts have been noted. When compared to SBM or SBM with FM, most studies found that chicks fed with BSF larvae experienced equivalent or even better development rates. Incorporating this insect meal into poultry diets could reduce feed costs without degrading bird performance, potentially increasing the profitability of the poultry industry.