Mosquito (Culex sp.)


    There are over 100 species of mosquitoes in North America and close to 3000 worldwide.  Mosquito adults must maintain their food in the form of a liquid.  The food may be plant juices (nectar, fruit juices, sap).  Only female mosquitoes of some species have mouthparts adapted for feeding on blood.  This blood may come from warm-blooded or cold-blooded animals. 
   
    Mosquito eggs must be laid in or very near water.  Some mosquitoes lay their eggs in masses known as rafts.  These egg rafts float on the top of the water and contain as many as several hundred eggs each.  Under optimum conditions, eggs usually htach within one to five days.  The larval stage is aquatic, feeding on bacteria, algae, and other tiny organisms found in the water.  Most mosquito larvae have breathing tubes located at the base of their tail.  They must expose the tail to the surface of the water in order to take in air and breathe.  The body is covered with brushy hairs that help it swim and prevent it from sinking.  Larvae undergo four growth periods known as instars.  For most species the entire larval stage lasts one to three weeks.  After the fourth instar in the larval stage, the larva rises to the surface of the water and undergoes a process known as pupation.  This process lasts about three to five minutes.  The mosquito sheds the larval exoskeleton and is now shaped like a comma (large head region, tiny tail region.)  The pupa can be very active, wiggling the tail to swim in rapid jerks.  The pupa's breathing tubes are at its head region, so its tail typically dangles downward when the pupa is at rest at the surface.  The pupal stage lasts one to three days, depending primarily on water temperature; warm temperature speeds development.  When it is time for the adult to emerge, the pupa is at the surface of the water, where the exoskeleton splits open.  Emergence takes about five minutes to complete.  The adult floats on the surface of the water until its exoskleton sclerotizes. 

Availability: Mosquitoes are available now. Contact Liz (eegraham@life.uiuc.edu) to schedule a pickup time (right after class is convenient). We will provide you with an egg raft. They will come in a small plastic container with water, so make sure your container at home is set up and ready to go BEFORE you pick them up.

Housing: Mosquito larvae are aquatic and should be kept in a shallow pan with water.  Make sure the water is dechlorinated.  Once the larvae are 10 days old, you should change the water in the pan.  You can transfer larvae to a new container with a plastic pipet, or you can pour all of the water through a fine mesh net to collect all of the larvae that way.  The net straining will stress your larvae more than the pipet will.  Once you have pupae, you should move them to a smaller jar of water that you can put inside of a mesh cage, or a larger jar with a mesh lid.  This will keep the adult from flying away if you are out of the room when it emerges.  If you keep your mosquitoes at room temperature, it should take two to three days for the eggs to hatch, ~15 days for larvae to molt to pupae, five to six days for pupae to molt to adults, and adults may live for several days or weeks. 

Food: We will provide you a powdered mosquito diet to feed your larvae.  You should add one pinch every three days.  Add a small amount of fresh water to the pan every time you add food.  If you do not use the diet, mosquito larvae also feed well on powdered milk dissolved in water.  If not enough powederd milk is used, the larvae grow very slowly.  If too much milk is used, a film develops on the surface and suffocates the larvae, so film must then be broken up.  If the film is a continual problem, the solution should be changed.  The amount of powdered milk to use depends on the volume of water and number of larvae to be reared.  Adults need a cotton ball soaked in water, and a cotton ball soaked in a 10% sugar solution to feed on.  Females require a blood meal to lay eggs, but it is entirely up to you if you want to take your rearing to that level.