I’ve heard some questions about mosquito spraying in our community and you can regularly see the signs in lawns. The system of best practices in mosquito control is called integrated pest management (IPM). Although originally designed for agriculture, this process can also applied to residential areas as well. The goal of IPM is to determine what the acceptable level of mosquitos is and then use mechanical and biological methods to control mosquitos. In IPM, pesticides should only be used in a targeted way to control outbreaks of disease or an out of control mosquito population as the benefits are only temporary. Unfortunately the people that sell pesticides in our community don’t do this – they want to sell a service. The extension service has a good summary of IPM here.

There are a number of reasons to avoid widespread preventative use of pesticides, the most common of which are a family of chemicals called pyrethroids.

• These chemicals kill all insects, not just mosquitos – including bees, butterflies and other pollinators.
• These chemicals are (usually mildly) toxic to humans (symptoms include “Abnormal facial sensation, dizziness, salivation, headache, fatigue, vomiting, diarrhea. Irritability to sounds or touch. Seizures, numbness.”).
• These chemicals wash away into waterways where they concentrate to harmful levels for aquatic life.
• Because of overuse, mosquitos are becoming resistant to these chemicals.

Pennsylvania has a registry for people hypersensitive to pesticides. This doesn’t prevent mosquito spraying near your house, but does require you to be notified if any spraying is done nearby. The penn state extension link above also has information on which spraying solutions that are most dangerous to children.

Spraying is meant to be a last resort in IPM. What measures can be taken before it comes to that? The first measure is to eliminate standing water where mosquitos breed. Turn over buckets, empty bird baths regularly, make sure rain barrels have a screen mesh covering them, check playsets, etc. You can also put a pump or other device in standing water to keep the water moving because mosquitos prefer still water. If standing water cannot be eliminated, there are biological agents that can be used. Larvicides are bacteria that attack mosquito larvae. Because they are bacteria that specifically target mosquito larva, they aren’t a danger to other insects or humans. Here’s one example.

Many birds, bats, frogs, turtles and other insects such as dragonflies hunt mosquitos, so providing habitats for these other animals can also be beneficial to mosquito control. The flip side of this is that pesticides can particularly hurt these predators as they’ll tend to accumulate in animals that eat insects.

Another method for control is to set up traps for mosquitos. Traps either attract mosquitos by a scent – a smell or CO2 (which mosquitos identify with animals) – or by environmental conditions like dark, standing water they think is a place to breed. Commercial traps like this one are available. There’s a number of homemade alternatives such as these. Here is another example that combines a trap with the larvicide mentioned above. Placement of these traps is important to their effectiveness. I’m going to give a few of these a try this summer and will try to report back on what worked best.

There is a place for in IPM for mosquito spraying. There are counties in PA with outbreaks of West Nile virus where spraying is targeted to control the outbreak for example. But mosquito spraying is not meant to be used as a regular, preventative technique as it often is by Nether Providence home owners. Overuse leads to extermination of beneficial wildlife and increased pesticide resistance, which in turn makes future mosquito-spread disease outbreaks more dangerous.