The presence and relative size of the subcostal pale spot to the preapical dark spot (SPC ratio) is thought to be an important diagnostic character for identifying adult Anopheles punctipennis. Variability of the SCP ratio on the wings of An. punctipennis was determined for four populations from California and Illinois. The SCP ratio was highly variable between individuals collected in the field and some individuals lacked the SCP altogether. SCP ratios were equally variable among siblings form isofemale lines. The SCP ratio, alone, is not a useful taxonomic character for distinguishing An. punctipennis from the closely related species, An. perplexens. Variability in the extent or presence of pale scaling on other wing veins suggests that patterns on individual veins are not particularly useful as diagnostic taxonomic characters.