The Mosquito/Copepod Kit
  A resource for Florida teachers and students.

Instructions for Rearing the Mosquitoes

Hatching the Eggs:

The eggs you received were laid by mosquito females on damp paper towels in our laboratory. The eggs are the tiny dark specs that cover the paper. After a dry period, these eggs will hatch when flooded. In nature this usually happens after rainfall or other flooding events. You can use tap water to flood the eggs, but the water must be free of chlorine. To get rid of the chlorine, let the water stand in an uncovered jar for at least 48 hours. Most mosquito eggs hatch faster if the water has a low oxygen content. To deoxygenate the water, add brewer's yeast to the water after it has been dechlorinated, cover the jar tightly and let stand for 24 hours. We will call water treated as above "prepared water".

Add the prepared water to a shallow tray, and then add the paper towel with the eggs. The side of the paper towel with the eggs should be face up and the towel must be totally submerged in the water. The eggs should begin to hatch into larvae within one half hour. If no hatching occurs, remove the paper towel, let it dry, and repeat the process with new prepared water. After 2-3 hours, remove the filter paper, add more prepared water if necessary, and add a small amount of the mosquito food.

Larval Development:

The amount of time that mosquito larvae spend in each of the instars depends on environmental conditions, particularly temperature and food supply. As a broad timetable, larvae should molt to the subsequent instar the following number of days after hatching: instar I to instar II - two to three days, instar II to III - three or four days, instar III to IV - four or five days, and instar IV to pupa - seven or eight days. Remember, these are only estimates; the actual times may vary.

The larvae will grow considerably during this time. Also, you should be able to see the discarded skins that they leave behind after each molt. Mosquito larvae feed continuously, so you should add a little food every other day. A scummy film will develop on the surface of the water and must be removed or the larvae will suffocate (larvae breathe air through a tube, the siphon, that must break the surface). To remove the film, skim the water surface with a paper towel every day. Add prepared water as needed to maintain the water level in the tray.

You can see the mosquito larvae actively scooping up food particles with the brushes near their mouth. This will be particularly visible with the larger larvae, but can be best observed under magnification (binocular microscope or good magnifying lens).

Pupae and Adults:

After about eight days, the fourth instar larvae will molt into pupae. The pupae are round to oval in shape and do not feed (stop adding food when the larvae pupate). They will whirl up and down in the water. Remember, adult mosquitoes will emerge soon (2-3 days) from the pupae so the pupae can't be left on the tray for very long or you will have adult mosquitoes loose in your classroom.

To observe the emergence of the adults, add prepared water to several jars until they are about ¼ full and transfer a few pupae to each jar, and then cover with the mosquito netting and a rubber band. Discard the unwanted pupae outdoors. After the adults emerge, you can keep them alive by placing the popsicle sticks inside the jar to act as a resting place for the adults, and placing a piece of cotton soaked in sugar water inside the container or on top of the netting. Before disposing of the adults, freeze them for several hours or fill the jar with hot water.