Electron diffraction determination of chain packing of a ketonic insect wax

Single crystal electron diffraction patterns are obtained from thin microcrystals of two polymorphic forms of a pure ketonic wax secreted by the wooly alder aphid, Prociphilus tessellatus. One crystalline form gives intensity data which agree well with the commonly observed O_⊥ methylene subcell. The unit cell constants for the projection are $\text{a = 7.52}\text{A}\text{?}$ and $\text{b = 5.05}\text{A}\text{?}$. The other polymorph, which is found less often, is a rectangular supercell with pseudohexagonal symmetry in the intensity-weighted hk0 reciprocal net. The supercell parameters in projection are $\text{a = 42.06}\text{A}\text{?}$, and $\text{b = 9.12}\text{A}\text{?}$ with the inner order hexad of intense spots occurring at 4.20 Å.