The larval lipids of the blowfly Lucilia sericata (Meigen) and the greater wax moth Galleria mellonella (Linnaeus), which differ markedly in their palmitoleic acid content, were separated on silicic acid columns into five fractions, viz. (1) cholesterol ester, (2) triglyceride, (3) unesterified fatty acid and cholesterol, (4) partial glyceride, and (5) phospholipid. The fractions were analyzed for individual fatty acids. For each species of insect, palmitoleic acid was found to be distributed among the glyceride and phospholipid fractions in its characteristic proportion in the total fatly acids of that species. Thus the difference in the proportion of palmitoleic acid in the lipids of the two species cannot be attributed to preferential exclusion of palmitoleic acid from the triglycerides of Galleria mellonella. In Lucilia sericata the principal fatty acids are partitioned among the glyceride and phospholipid fractions to virtually the same degree, but in Galleria mellonella they are partitioned unevenly. This unevenness in partitioning is most evident with linoleic acid, which is relatively high in the phospholipids.
