by Dawn R. Cole

Created on: July 08, 2008

SCRATCHING THE SURFACE: WHY FEMALE MOSQUITOES NEED BLOOD

The world is populated with roughly 3,000 species of mosquitoes. Both sexes are actually nectar feeders but in many species, the female members are capable of hematophagy (sucking the blood from other animals.)

WHY BLOOD?

Female mosquitoes do not require blood for their own survival. Blood contains vital substances, like protein and iron, which aid in the development of her offspring.

Females are driven to obtain blood for egg production.

MOSQUITO LIFE CYCLE

Mosquitoes go through 4 stages of development:
* Egg
* Larva
* Pupa
* Adult

Some species of females choose to deposit their eggs in moist areas that are muddy or contain fallen tree leaves. The accumulation of water from rain or high tides stimulates the eggs to develop into larva.

Other females will lay their eggs directly on still waters. The water is often stagnant and closer to residential areas. Ditches drain basins, gutters, birdbaths, ponds, or unused children's pools are all prime locations for mosquitoes to lay their eggs. In either case, it does not take long before the eggs hatch into larva.

The heat of the summer sun allows the larvae to grow at a rapid pace and become pupae. (Both the larval and pupal stages occur in water.) It only takes a week for the pupae to develop and emerge from the water as an adult mosquito.

As soon as the adult is released from its aquatic womb, it begins to mate. Males normally emerge first and stay close to their birth site, where they wait for the females to appear. Time is of the essence because adult mortality is very high. The male only lives for a short time (6 -7 days) after mating and the normal life span of the female ranges between 2 weeks to 5 months.

After mating, the females seek out a blood source to obtain the needed elements for her eggs. After digesting her first blood meal and laying her first batch of eggs, she will seek out another meal to produce a second batch of eggs and continue the routine until her demise.

HOW DO FEMALES GET THE BLOOD?

Mosquitoes are equipped with a long proboscis that allows them to pierce through layers of skin and suck. Before the female extracts any blood from the tiny hole, she injects saliva into the wound. The chemical composition in her saliva acts like a mild painkiller and prevents the blood from clotting. She is able to insert her narrow food canal and successfully draw out the blood.

HOW DO THEY CHOOSE THEIR VICTIMS?

Female mosquitoes use our exhaled CO2 as a location device.

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