Mosquitoes in Ohio
In 2015, there were 34 human cases of West Nile Virus in the State of Ohio resulting in 4 deaths. Of those 34 cases, 1 of them were reported in Franklin County. There weren’t veterinary cases in Franklin and Delaware Counties. These cases can all be linked directly to mosquito bites. There were a total of 2,234 mosquitoes that tested positive for being infected with WNV, and of those a whopping 713 were found in Franklin County. The reported cases may be low as Franklin County had the highest number of WNV positive mosquitoes reported. West Nile Virus is most deadly in younger or older populations or those that are immunocompromised such as those receiving treatment for cancer. The median age for the 34 human cases was 59 years of age.
Ohio also reported 4 cases of La Crosse encephalitis, another mosquito-borne disease, one of which was in Delaware County. La Crosse encephalitis appears to target younger people.
(Source: Ohio Department of Health)
Mosquito Life Cycle
Mosquitoes go through a process known as metamorphosis: Meta means change and morph means form. There are four distinct changes in their life cycle:
- Eggs: Some mosquito species lay up to 300 eggs clustered in rafts that float on top of the water. With proper weather conditions, eggs will hatch in 1-5 days. Most eggs need still and shallow water, although some are laid in areas that will eventually be under water. All eggs need water to hatch. They can survive for up to 7 years.
- Larva: Mosquito larvae (plural) are also known as wrigglers because they are worm-like and swim by wiggling through the water. Larva live in water, but must breathe air. They breathe through a tube known as a siphon. The larva molts 4 times, growing in size each time and are fully grown in 7-14 days. They are part of the food chain and they feed on small particles like bacteria and yeast in the water. In turn, they are eaten by fish, frogs, diving beetle larva, dragonfly naiads, and crayfish.
- Pupa: The pupa also uses breathing tubes called trumpets. This stage does not feed on anything. It is also known as a tumbler because when it swims it tumbles erratically and then floats back to the surface. This stage only lasts 1-3 days.
- Adult: The adult female mosquito is the culprit of your bites. Male mosquitoes feed on plant material. The biggest distinction between the two physically is the antennae. Males have large, bushy antennae. The male mosquito lives only 10-20 days while the female mosquito can live for up to 3 months.
- 1st Generation: Female Mosquito + 1 Blood Meal = 300 Mosquitoes (150 Females)
- 2nd Generation: 150 Female Mosquitoes +150 Blood Meals = 45,000 Mosquitoes (22,500 Females)
- 3rd Generation: 22,500 Females + 22,500 Blood Meals = 6.75M Mosquitoes (3.375M Females)
- 4th Generation: 3.375M Female Mosquitoes + 3.375 Blood Meals = Over 1 BILLION Mosquitoes!
- All in less than one month, from one female mosquito (assuming all potential eggs survive)
Mosquito larvae can be found in numerous habitats. Each habitat produces specific mosquito species and show a seasonal progression of species. Habitats can be generally grouped into 4 types:
- Running water (streams, uncommon in US)
- Transient water (flooded areas, ditches)
- Permanent water (lakes or ponds)
- Containers (your biggest backyard problem)