The gills retain their color after preservation but gills are fragile and more often than not, break off in preserved specimens. Most keys use the spicules on the saddle as the major character to separate these two species. Aedes stimulans has well developed spicules on the posterior portion of the saddle. The saddle of Ae. Proper placement of the specimen is essential to accurately assess the presence or absence of spicules.
Spicules are tiny teeth that protrude from the saddle.
In most cases, they cannot be seen by looking directly down on the saddle. If the specimen is positioned on a white background with the siphon pointing directly up, the spicules on the posterior margin of the saddle stand out as sharp little teeth. They are very obvious in Ae. As a result, the posterior margin of the saddle is raggedly toothed in Ae. Aedes stimulans possesses a character that does not appear in any key.