Acknowledgements
We are grateful for Ms Juan Guan and Dr Chris Holland for help on compressive tests, Mr Maxime Boulet-Audet and Ms Imke Greving for instruction of FTIR tests, Mr Xiafu Shi and Mr Gwilym Davies for helping with the cocoon photographs. We particularly thank Prof Richard S. Peigler for checking the silkmoth species spelling. This project is funded by AFSOR (Grant No. F49620-03-1-0111), USA and European Research Council (SP2-GA-2008-233409).