The week of June 26 to July 2, 2016 has been declared National Mosquito Control Awareness Week by the American Mosquito Control Association (AMCA). The goal is to educate the general public about the significance of mosquitoes in their daily lives and the important service provided by mosquito control workers throughout the United States and worldwide.
To kick off the week, Richard Levine, the editor of the Entomology Today blog, spoke with Joseph Conlon, technical advisor of the AMCA.
Richard Levine: When did Mosquito Control Awareness Week begin and why?
Joseph Conlon: The original resolution declaring the week each year that includes the date of June 26th as Mosquito Control Awareness Week was drafted in 2003 and signed off by then AMCA president, Dr. Fred Knapp. It arose, at least partly, in response to the emergence and spread of West Nile virus, particularly the large outbreak in 2002.
RL: What can homeowners do to keep mosquitoes out of their backyards?
JC: Given certain species of mosquitoes’ flight ranges of 1 – 40 miles, it’s difficult to keep mosquitoes out of the yard by cleanup of your own premises. Nevertheless, mosquitoes that prefer to oviposit in containers such as those that transmit Zika and dengue viruses can be significantly reduced in one’s yard by removing or cleaning out all containers that hold water every four days. I’d advise homeowners to:
· Get rid of old tires, tin cans, buckets, drums, bottles, or any water-holding containers.
· Fill in or drain any low places (puddles, ruts, etc.) in the yard.
· Check air conditioning drain pans.
· Keep drains, ditches, and culverts free of weeds and trash so water will drain properly.
· Keep roof gutters free of leaves and other debris.
· Cover trash containers to keep out rainwater.
· Repair leaky pipes and outside faucets.
· Fill in tree rot holes and hollow stumps that hold water.
· Change the water in bird baths and plant pots or drip trays at least once each week.
· Store boats covered or upside down, or remove rainwater weekly.
· Keep grass cut short and shrubbery well trimmed around the house so adult mosquitoes will not hide there.
· Maintain screening: ensure door and window screens fit tightly and holes are repaired.
· Installing bird or bat houses to attract these insect-eating animals has been suggested as a method of mosquito control. However, there is little scientific evidence that this significantly reduces the mosquito population around homes.
RL: A lot of “natural” products are being marketed, such as wrist bands, sonic devices, and “organic” repellents. Do any of them really work?
JC: A recent landmark USDA study compared the repellency of OFF! Clip-On Mosquito Repellent (Metofluthrin 31.2%) and the Terminix ALLCLEAR Sidekick Mosquito Repeller (Cinnamon oil 10.5%; Eugenol 13%; Geranium oil 21%; Peppermint 5.3%; Lemongrass oil 2.6%), which are personal diffusers. The OFF! Clip-On and Terminix ALLCLEAR Sidekick reduced biting on the arms of volunteers by 96.28% and 95.26%, respectively, for Aedes albopictus (the Asian tiger mosquito), and by 94.94% and 92.15%, respectively, for Culex pipiens (the northern house mosquito).
In a second trial conducted to compare these devices directly, biting was reduced by the OFF! Clip-On and the Terminix ALLCLEAR Sidekick by 87.55% and 92.83%, respectively, for Aedes albopictus, and by 97.22% and 94.14%, respectively, for Culex pipiens. There was no significant difference between the performances of the two diffusers for each species. Be advised, though, that this level of repellency is only obtained in areas of little or no wind movement. Breezes will waft the repellent fraction away from the body, reducing repellent concentration and compromising repellency.
This study also compared various other devices claiming repellency to mosquitoes. Products used were the Super Band Wristband (22% Citronella oil), the PIC Citronella Plus Wristband (Geraniol 15%; Lemongrass oil 5%, Citronella oil 1%), the Sonic Insect Repeller Keychain, the Mosquito Guard Patch (oil of lemon eucalyptus 80 mg), an adhesive-backed sticker for use on textiles, and a transdermal patch called the Mosquito Patch (vitamin B1 300 mg). It was determined that the sticker, the transdermal patch, wristbands, and sonic devices did not provide significant protection to volunteers compared with the mosquito attack rate on control volunteers who were not wearing a repellent device.
Individuals preferring “natural” remedies should keep the following in mind: Often-recommended ingredients that have been tested and don’t exhibit repellency to any noticeable degree include absinthe, andiroba, anise, basil (holy), basil (sweet), bergamot, billy-goat weed, tropic ageratum, cedar (Deodar), cypress (Chinese weeping), eucalyptus (blue), fennel, Chinese ginger, fishpoison, garlic (Oriental), geranium (rose), and ginger.
Repellent ingredients that demonstrate some measure of repellency but haven’t been marketed due to toxicity issues, problems with cost, or difficulties in formulating them to volatilize at a requisite rate to maintain repellency over time include basil (hoary or hairy), betel pepper, cassia, catnip, cedar (Alaskan yellow cedar), cedar (western red cedar), celery, chastetree (roundleaf), citronella, citronella (Java), clove, coconut oil, embrert, eucalyptus (red), eucalyptus (lemon), fever tea, Huon pine, labrador tea, lime, lemon grass (east Indian), lily-of-the-valley (European), litsea, makaen, Mexican tea, neem, niaouli, palm oil, palmarosa, patchouli, pennyroyal, pine (Scots), pyrethrum, rue (fringed), soy bean, and thyme
Repellent ingredients that have been recommended over the Internet via testimonials that can be dangerous to human skin and physiology if misused include anise, basil, bergamot, niaouli, cassia, cedar (Alaskan yellow cedar), citronella, citronella (Java), citrus oils, clove, fever tea, geranium, ginger, Huon oil, lemon grass, lime, litsea, marigold (wild), Mexican tea, mint, nutmeg, palmarosa, pennyroyal, pine (Scots), rosemary, rue (fringed), thyme, violet, and ylang-ylang
RL: What about mosquito traps that entice females to lay eggs inside of them. Can they be effective?
JC: They can indeed capture significant numbers of mosquitoes, but not in numbers high enough to exert sufficient downward pressure on mosquito populations to effect large scale control. They are usually a component of a more comprehensive integrated vector management strategy.
RL: In addition to blood meals, mosquitoes drink nectar from flowers and are known to be found near plants, especially under leaves. Do they somehow drink the sap from the leaves? And are there some plants that they prefer more than others?
JC: Mosquitoes do not drink sap from the leaves but, as you state, drink nectar from flowers in order to gain energy for flying. I’m not aware of any preference for certain plants, but I would not be surprised if there were.
RL: In the recent past a lot of resources were used against Culex mosquitoes because of West Nile virus. Now that Zika, dengue, and chikungunya are appearing in the U.S., should the focus be on Aedes mosquitoes instead?
JC: I think we should be preparing control capacity for a wide range of mosquitoes that transmit disease. While Zika is on the public’s radar screen, West Nile remains the principal mosquito-borne disease threatening the average citizen.
Richard Levine is Communications Program Manager at the Entomological Society of America and editor of the Entomology Today Blog.