Female mosquitoes need blood to nourish their eggs

You wanted to know

A young patron at the Cook Memorial Public Library in Libertyville asked, "Why do only female mosquitoes bite?"

Spring's warmer temperatures bring on the three Bs - blooming flowers, budding trees and buzzing mosquitoes.

These tiny creatures can be found nearly everywhere on Earth thanks to their attraction to human body odor. Some mosquito species were drawn by people-power across continents as human populations spread.

These tiny travelers carry with them uninvited guests - deadly diseases such as malaria, dengue fever, chikungunya, West Nile, encephalitis and others that can harm humans and animals. As a result, mosquitoes are the most dangerous animals on the planet.

However, they are also important food for fish, birds, bats and spiders.

Why do only female mosquitoes bite?

"Females are the only ones to lay eggs, and they need the extra protein from blood to lay eggs," said Andy Snider, Brookfield Zoo curator of herpetology and aquatics.

While only some of the 3,000 species of mosquito require blood for egg-laying, said Dr. C. Roxanne Connelly, professor, extension medical entomology specialist at University of Florida, they also draw on other sources for nutrition.

"Both males and females feed on plant nectars for a carbohydrate source. This provides them with energy for flight, but the females require that extra source of nutrition from blood for nourishing the eggs that she will deposit," Connelly said.

Other insects that follow the female-only bloodsucking pattern are midges and black flies. Insects in which both males and females ingest blood include lice, bedbugs and fleas.

It seems some people are more frequently targeted by mosquitoes than others.

"Recent studies have shown that there seems to be a masking odor that some people give off that mosquitoes find bad smelling," Snider said, so they are less likely to become mosquito nourishment.

These little guys have amazing senses and can identify carbon dioxide emanating from humans as they exhale from a distance of 75 feet, Snider explained. That gas is another attraction for these tiny blood suckers, signaling them to buzz by and grab a bite.

Knowing mosquitoes can pass along a host of viruses and diseases, do your best to avoid them, Connelly cautioned.

"The best way to avoid the mosquito-borne diseases is to be aware of local conditions, that is, pay attention to messages from the Centers for Disease Control and local health departments and mosquito control agencies concerning local risks of transmission," she said.

"If you will be in an area where you might be exposed to mosquitoes or mosquito-borne diseases, wearing effective repellents is a good idea, or just staying indoors to avoid biting time would work too."

The tiny buzzing bugs have been around for millions of years. Some have been fossilized in amber, a tree sap from ancient forests. These insects have a life cycle of weeks to months, with females outliving males. Larvae overwinter in frozen water and spring to life as temperatures rise.

Being a dog lover, Connelly was drawn to study mosquitoes because they can carry heartworm, a deadly parasite that burrows into a dog's organs, in particular the heart.

"When it came time to decide on the research project though, I knew that I could not use dogs in my study without being heartbroken, so I began studying the habitats of some of the malaria mosquito in Louisiana," Connelly said.

"Over the years, I have learned a lot about managing mosquitoes, and in my current position, I include educational pieces about protecting dogs from mosquito bites and giving your pets a heartworm preventive, so I can still address my original concerns about dogs."

Connelly is past president of the American Mosquito Control Association and the Florida Mosquito Control Association.

Check it out

The Cook Memorial Library in Libertyville suggests these titles on mosquitoes:

• "Bzzz, Bzzz!: Mosquitoes in Your Backyard" by Nancy Loewen

• "Mosquito Bite" by Alexandra Siy and Dennis Kunkel

• "Mosquitoes: Tiny Insect Troublemakers" by Sandra Markle

• "Swamp Chomp" by Lola Schaefer; illustrations by Paul Meisel

• "Why Mosquitoes Buzz in People's Ears," retold by Verna Aardema

• "Ricky Ricotta's Giant Robot vs. The Mutant Mosquitoes from Mercury" by Dav Pilkey