The non-waxy component of the armored-scale insect shield

Approximately 50% of the shield of the Florida red-scale (Chrysomphalus aonidum) is composed of a dark brown non-waxy material completely soluble in 0.5 M KOH and precipitable with 0.1 M HCl. The absorption spectrum shows a pronounced shoulder at 250-270 nm with no visible peaks. The infrared spectrum shows major peaks at 2.9, 6.1 and 9.23 μm. The material contains 3.7% nitrogen, and amino acids account for only 15% of the total weight. The non-waxy fraction does not contain DNA, RNA or carbohydrate. The bulk of the fraction is heterogeneous in size with a molecular weight of at least 200000. It is suggested that the non-waxy fraction might be a polyphenol or melanin-like compound and that hardening of the shield involves enzymatic polymerization of a tyrosine derivative.