Re-analysis of the methylalkanes of the grasshoppers,Melanoplus differentialis,M. packardi and M. sanguinipes

Gas chromatography-mass spectrometry was used to determine the structures of the methyl branched alkanes of the grasshoppers Melanoplus differentialis (Thomas), M. packardii (Scudder) and M. sanguinipes (Fabricius). The branched hydrocarbons were composed of 2- and 3-methylalkanes and internally branched mono- and di-methylalkanes. The major dimethylalkanes were a homologous series from C₃₃ to C₅₅ and had nine methylenes between the branch points rather than three as reported by Soliday et al. (1974) for M. packardii and M. sanguinipes. Unexpectedly, the homologous series with nine methylenes between branch points did not extend to the C₃₁ dimethylalkanes. The C₃₁ dimethylalkanes were identified as 9,21-dimethylhentriacontane (11 methylenes between the branch points) in M. packardii and M. Sanguinipes and 11,19-dimethylhentriacontane (seven methylenes between the branch points) in M. differentialis.