Gender sensitivity to ambient heat, despite well known in insect species, how it manifests during young and late larval instars ofBombyx moriis still unclear. To uncover this cryptic feature, different instars male and female larvae were subjected to varied thermal stress separately and sex-stage specific expression of proteins was investigated. Interestingly, heat shock proteins (HSPs) 90 and 70 were expressed differently in all the instars and also between male and female larvae as confirmed by immunoblot assay. Besides up- and downregulation of few HSPs and other normal proteins, discreet expression of protein was noticed in the two-dimensional gel electrophoresis of male than female larvae which were identified as HSP70 by mass spectrometry. Furthermore, quantitative polymerase chain reaction results show 3.98- and 4.86-fold higher levels ofBmhsp70andBmhsp90transcripts in male and female larvae, respectively, as a response to 40 degrees C heat shock (HS) treatment. Conversely, in spite of the massive production of HSPs due to HS at 45 degrees C, all the larvae were found dead, which is a strong proof of concept for autophagy. Comparatively, female larvae HS at 40 degrees C succeed to spin cocoons with increased weight and silk contents than non-HS larvae. Comprehensively, in the present study, we have noticed a strong correlation for the first time thatBmhsp90andBmhsp70genes expressions due to thermal stress are not only sex specific but also explicit preferential and coordinated action on survivability and biosynthetic potential of the silkworm,B. morilarvae during different instars.