Insect Repellent Questions & Answers

Spring and summer are times of the year when mosquitoes can make outdoor activities less pleasant. Puddles, ditches and artificial containers serve as excellent breeding grounds for these pests. Some types of post-flood mosquitoes do not transmit diseases but they still bite people and can be a significant nuisance. Other types of mosquitoes transmit diseases such as West Nile virus. The Missouri Department of Health and Senior Services wants to help you and your family stay safe from infections that are transmitted by mosquitoes and tick bites. If you are unsure about the basics of using an insect repellent, here are some Q&As to help:

Why should I use an insect repellent?

Using an insect repellent allows you to continue to play and work outdoors but avoid mosquito and tick bites. Avoiding mosquito and tick bites can prevent West Nile virus, ehrlichiosis and Rocky Mountain spotted fever disease, all of which can cause serious illness and even death.
People also try to avoid bites for other reasons besides disease prevention. For example, some people experience an allergic reaction to tick or mosquito bites that causes skin reactions like swelling, redness, itching or pain. Insect bite wounds can develop secondary infections, too.

When should I use a repellent?

Apply repellent when you are going to be outdoors and will be at risk for getting bitten by ticks or mosquitoes.
Depending on yearly climate variation, in Missouri, biting insects can be active in the winter, early spring and late autumn.
Even when you don’t notice them, there is a chance ticks and mosquitoes will notice you. Mosquitoes can detect a prospective host from as far away as 100 feet. The lone star tick, which is Missouri’s most common tick, can actually detect the footsteps of a potential host and start running towards it within a matter of seconds.

How do insect repellents work?

Biting insects have antennae and other sensory organs that serve as a kind of a detection system, alerting them when a human or animal host is nearby. Insect repellents work by blocking these detection systems, preventing insects from homing in on their source.
The best repellents contain a proven active ingredient that will provide protection from bites for a long period of time from just one application.

How much repellent should I apply and exactly where?

Repellents that contain DEET are effective and long lasting. The product label provides detailed instructions on how to apply a DEET-based repellent.
A repellent with DEET only protects the areas to which it is applied. The application of DEET to a few points of the body, therefore, will not "cloak" the user in protection.
Insect repellent should be applied as a thin layer, covering the entire exposed skin surface evenly. Heavy application is not necessary to achieve protection.
Using the hands to rub a spray or lotion repellent into exposed skin helps ensure even distribution of the product.
Remember to apply only to exposed skin and/or clothing. Do not use repellents under clothing.
DEET should not be applied to synthetic fabrics such as rayon or to plastics, because it can damage these products.

How often should I apply insect repellent?

Follow the directions on the product you are using in order to determine how frequently you need to reapply repellent.
Be observant of conditions that may call for additional repellent. Perspiration, high humidity or getting wet may mean that you need to reapply repellent more frequently.
If you are not being bitten, it is not necessary to reapply repellent.

Can any insect repellent be used on kids?

Parents should choose the type and concentration of repellent to be used by taking into account the amount of time that a child will be outdoors, exposure to mosquitoes and the risk of mosquito-transmitted disease in the area. This information is found on the label directions.
The American Academy of Pediatrics (AAP) recommends that a 10% - 30% concentration of DEET be used only on children over two months old.
The label directions for oil of lemon eucalyptus specify that it should not be used on children under three years of age.
Do not allow children to handle repellent products, and do not apply to children’s hands.
When using on children, apply repellent to your own hands and then put it on the child.
Parents should store all pesticides, including insect repellents, safely out of the reach of children.

I have noticed that stores sell DEET in concentrations of anywhere from 5% to 100%. How do I know which strength is right for me?

There is no one right answer to this question. The various concentrations of DEET are out there to address different needs. As a general rule, higher concentrations of DEET will offer longer-lasting protection, but this effect tends to level out at concentrations of DEET over 50%.
Under most circumstances of casual use, a product with 10% - 35% DEET will provide long-lasting protection against mosquitoes.
Repellents containing three other active ingredients are also effective against mosquito bites: picaridin, oil of lemon eucalyptus and IR3535.
In order to protect against tick bites, using a higher concentration of DEET (between 20% and 50%) is preferable.
People over age 40 or whose immune system is weakened can develop more serious tick-borne illnesses and should consider using up to 50% DEET as well.
At this time, products containing DEET are the only repellents applied to skin that are effective against tick bites.

Is there a stronger solution recommended for Missourians planning to camp or who work outdoors?

If you're going to be outdoors for extended periods of time, DHSS recommends a product called permethrin, which is designed for application to clothing and not to skin.
Permethrin is a pesticide and a repellent. It will kill ticks and mosquitoes that come into contact with treated clothing, shoes or camping gear. Safe use of this product requires a careful reading of the label and following instructions to the letter.
Permethrin is not a repellent you decide to pick up on your way out of town – its use requires planning and advanced preparation.
Permethrin bonds with the fabric of clothing, shoes and camping gear after it dries. For this reason, pretreated clothing and equipment can provide protection against mosquitoes and ticks through multiple washings.
Treat your clothing before you pack for your next hike, camping trip or outdoor adventure.
Choose a sheltered area outdoors to make spray applications to your clothes.
When permethrin products are applied to clothing, the spray should be allowed to dry completely before the clothing is worn.
Never use permethrin on your skin.

In addition to using insect repellent, are there other ways to avoid insect bites?

For the prevention of tick- and mosquito-borne disease, public health professionals recommend using multiple bite prevention strategies, including:
Clothing – As a sole method of protection, unfortunately, physical barriers have their drawbacks, including that they tend to be hot, limit mobility and do not protect exposed skin.

Wear light-colored clothing so ticks can be seen more easily.
Wear long pants tucked into boots.
Tightly-woven socks protect better against seed ticks.
Densely woven or mesh clothing can reduce the likelihood of being bitten.

Tick-checks – The longer an infected tick is attached to a host, the greater the chance of being infected with a tick-borne germ.

Check your clothes periodically for ticks while you’re still outdoors.
Do a complete body check after you have walked or hiked through any vegetation.
Check pets before bringing them inside.
Showering and laundering your clothes after being outdoors has been shown to be effective in preventing ticks from being attached long enough to transmit germs.

What should I do if I find an attached tick?

Use fine-tipped tweezers to grab an attached tick’s head close to the skin and pull up with a steady motion until the tick is removed.
Do not dig out tick mouthparts that are embedded in the skin. Clean the bite and watch for secondary infection. Normally, the skin will expel embedded tick mouthparts similar to expelling a splinter.
Tick can be killed by encasing it in tape and then discarding it in the trash.
Mark the day you found it on your calendar.
For most people, symptoms of Missouri's tick-borne diseases usually appear less than two weeks after an infected tick bite.

Call a doctor if you get a sudden fever with chills, severe headache, fatigue or muscle aches in this time frame. Tell doctor the day of likely attachment and day tick was removed.

Can I order free resources from the state?

Yes, use this order form to request items.

Topic Menu

Contact Information