Many of the parasites ingested with a blood meal by mosquitoes cause midgut damage. Cellular proliferation (mitotic activity) to repair the site of injury increases RNA and DNA levels. Squash smears were made of mosquito abdomens. Smears were agitated in the 0.01% Acridine Orange (basic orange 14) solutions, pH 6.0 for 10 seconds. Smears were rinsed and mounted 1/10 M CaCl2 solution. Smears were viewed with a fluorescence microscope using a BG 12 filter. Positives were apparent with brilliant red fluorescing.