Insects mainly depend on host plants for their dietary requirements which are fulfilled by them for various purposes including reproduction, growth and developments. The pertaining literature reveals that the growth and moulting hormones viz. ecdysone, juvenile hormones and even pheromones is basically lipid containing cholesterol, fatty acids and sterols. This is why, in the present study, the work has been carried out on lipid contents of plant Ricinus communis L. related to utilization of lipid by Bombyx mori L. The effect of lipid fraction of leaves ether extract of Ricinus communis L. were found to be growth retarding and it took more time to moult in to next instar when extract was applied topically on 1st instar larvae. The results shows that the female reared on treated leaves laid 110 eggs less than the normal female moths by testing the significance of difference between number of eggs laid by a female reared on untreated leaves and that of a female reared on treated leaves. The value of 't" test came to be significant (15.92) which is much greater than the table value of "t" (2.14) for 18% of freedom at 5% level of significance. The results also show that the hatching of the eggs was reduced by 36% in response to the feeding on treated leaves. Testing the significance of difference between hatching of the eggs of the female reared on untreated leaves and that of the eggs of female reared on treated leaves, the value of "t" obtained was 23.25 which is much greater than the table value, hence it is highly significant (p<0.05). This shows that plant extracts markedly affects and reduces the hatching of the eggs. The results also show that larvae fed with treated leaves were reported very poor in growth as compared to those fed with untreated leaves. This may be due to some insecticidal activities found in castor leaves. This is why, the feeding of treated leaves resulted 46.6% larval mortality while untreated leaves showed 6.6% larval mortality only. Similarly, the results of feeding of treated leaves on pupae were reported 37.5% mortality and untreated leaves feeding showed 7.1% mortality of pupae. These results suggest that Ricinus communis L. extract possess phytochemical which cause serious mortality. The larvae which died after feeding of treated mulberry leaves showed sign of rapid dehydration which shows insecticidal property against Bombyx mori L.