Learn the science behind the itches of summer

I adore summer.  In fact, it’s one of my four favorite seasons!  

Who doesn’t love the longer days, sunny skies, and warmer temperatures?

For me, as the mother of two adventurous boys, summer means more time spent outside exploring nature and having fun.  Since the school year is done, I also have more time to spend gardening.

But summer isn’t all sunshine and rainbows. Increased time spent out of doors at this time of the year can lead to exposure to one or more of the scourges of summer: poison ivy, chiggers, and mosquitoes.

I’ve had poison ivy once in my life, and that was enough.  Not only did it ruin a family vacation, but I racked up a hefty doctor’s bill after developing complications.

Chiggers love me, and plague me each and every summer.  

As a Florida native, I know about mosquitoes all too well. Did you know that mosquitoes—those annoying, buzzing nuisances—are actually considered to be THE most dangerous animal in the WORLD? How is that possible? Read on to learn more.

Benjamin Franklin once said, “An ounce of prevention is worth a pound of cure”, and the best way to avoid the misery of poison ivy, chiggers, and mosquitoes is to steer clear of them.   

 In this post, I explain the science behind the itches of summer, dispel some myths, and provide steps you can take to protect yourself this season.

Poison Ivy, Poison Oak, and Poison Sumac

How to Spot Them

“Leaves of three, let it be” is a worthwhile saying most of us were taught as children. 

Unfortunately, it doesn’t always apply.

While poison ivy has leaves in clusters of three, that’s not always the case for its cousins.

While avoiding leaves of three will protect you from poison ivy, it won’t protect you from poison oak and sumac. My advice is to become acquainted with how each of these plants look.*  

Poison ivy, poison oak, and poison sumac are common causes of summer misery.  Learning how to identify these plants can help you avoid the misery they can cause.
Clockwise from top left: The new leaves of poison ivy are often reddish. The bright green leaves of established poison ivy are seen growing among ferns. Because the leaves of poison ivy are often some of the first to turn color in the fall, they easily stand out.  This makes fall a great time to locate and remove any poison ivy on your property. When certain species of poison ivy grow as a vine, it may attach to surfaces using hair-like roots.

Poison ivy species are found throughout the continental United States, and can grow as a ground cover, as a bush, and as a vine.

Depending on the species, leaves can be smooth or serrated but always grow in groups of three: one on each side and one in the center.  

The leaves can change color. New growth often appears red while older leaves are bright green. During the fall, the leaves can turn yellow, orange, or red. Some species may produce white berries.

Poison oak  grows as a shrub or a vine, and while many species have leaf clusters in groups of three, others have clusters in groups of five to seven.  The leaves of poison oak can be fuzzy or textured, often with a rounded tip. The plants may produce berries that are yellowish-green.

Poison sumac grows as a tall shrub or low tree, and it prefers to grow in wet, boggy areas.  Leaves grow in clusters of 7 to 13, and the plant may produce yellow-white berries.

What Causes the Itch?

Poison ivy, poison oak, and poison sumac are all members of the Toxicodendron genus of the Anacardiaceae family.  These plants all contain  urushiol oil, the substance that triggers a miserable allergic reaction in 85% of people.  In these individuals, as little as one billionth of a gram of urushiol oil is enough to trigger a reaction.

Prevention Tips and How to Find Relief

If you fear you’ve exposed yourself to one of these plants, wash the area immediately with soap and water.  Some advise cleaning the area with rubbing alcohol, since it is an effective solvent for oils.

If you develop an allergic rash following exposure to urushiol, use over-the-counter medications to control the itching.  Calamine lotion and oatmeal baths may provide relief. Avoid scratching the rash, as breaks in the skin could lead to infection.  While allergic reactions are often treatable at home, seek medical help if you need it.

Other Useful Information

Urushiol oil---the substance responsible for causing the itchy reaction after exposure to poison ivy, poison oak, or poison sumac---is present in the peels of mangoes and in raw cashews.
Urushiol oil is present in the peels of mangoes and in raw cashews.
  • The poison ivy rash is not contagious: you can’t “catch” poison ivy.  However, urushiol oil can be spread from person to person, and can be transferred from contaminated gardening equipment and even pet hair.  What’s more, urushiol oil can linger on surfaces (sometimes for years). This is why it’s so important to be able to identify these plants, and to take steps to thoroughly clean anything that may become contaminated with the oil
  • Despite what you may have heard, the fluid in the blisters of rashes caused by these plants do not contain urushiol oil and therefore can not spread the rash.
  • NEVER BURN THESE PLANTS.  While I completely understand the desire to kill these plants with fire, it’s a really bad idea.  As the plant is burned, the oil is released into the air and can rapidly spread up to miles away. If inhaled, it can cause lung inflammation, difficulty breathing, and even fatal respiratory distress
  • Because urushiol is present in the leaves, roots, and stems of these plants, they remain dangerous even in the wintertime.
  • Think you’re one of the lucky ones who isn’t allergic to urushiol?  Good for you! Just remember that it sometimes takes multiple exposures to urushiol to develop an allergy.  So proceed with caution
  • If you are sensitive to urushiol oil, you may want to have someone else peel your mangoes.  You’ll also want to steer clear of raw cashews. Mango and cashew plants belong to the same genus as poison ivy, sumac, and oak. Urushiol oil is present in the peels of mangoes and in raw cashews. The oil is not present in the fruit of the mango, so you should be fine eating the fruit.  Roasting cashews destroys the urushiol oil, so eating processed cashews shouldn’t cause an allergic reaction to urushiol.


How to Spot Them

The biting form of a chigger is too tiny to see with the naked eye.
The life cycle of a chigger is divided into four stages. Only chiggers in the larval stage bite. Note that chigger larvae have six legs, while nymph and adult forms have eight legs.

Chiggers (also known as red bugs, berry bugs, or harvest mites) aren’t insects.  Like spiders and ticks, they are part of the arachnid family.

Their life cycle is divided into 4 stages:  egg, larvae, nymph, and adult.

Only chiggers in the larval stage bite: the nymphs and adults feed on plant matter.  Chiggers are incredibly small, so tiny that they’re often hard to see. Larvae range in size from 1/120 to 1/150 of an inch! The harmless adult form is larger (1/20 of an inch).  

Where and When Are They Found?

Adult chiggers don't bite
A chigger on my deck. I placed the petunia beside the chigger (inside red circle) to provide scale. A close up of the chigger is found in the top left corner. Since this chigger has eight legs, it is either a nymph or an adult and won’t bite.

Once chigger eggs hatch in the spring and summer, larvae climb onto vegetation and await their prey.  They are often found in vegetation, especially in overgrown areas. I have also observed them on my deck and picnic table.  They are most numerous in the late spring and early summer, when many people spend time working in the garden.

Chiggers aren’t picky:  they will feast on animals (including pets) in addition to humans. That’s means chiggers may be able to hitch a ride inside your house on Mittens or Fido.

What Causes the Itch?

Chiggers pierce the skin and inject saliva into the host, capable of liquefying skin cells.  Some of these cells harden to form a stylostome. The host immune response to chigger saliva causes an itchy welt.
Chiggers pierce the skin and inject saliva into the host, capable of liquefying skin cells. Some of these cells harden to form a stylostome.

Chiggers don’t actually “bite”.  

Instead, they pierce the skin and inject saliva containing digestive enzymes.  These enzymes liquefy skin cells, some of which harden to form a tube called a stylostome. This stylostome acts like a straw through which the chigger is then able to suck up and ingest the remnants of digested tissue.  Feeding sessions can last up to 4 days if the chigger isn’t dislodged from its host.

The misery of chigger bites is due to the host immune response to the digestive enzyme found in chigger saliva.  

Prevention Tips and How to Find Relief

To avoid chiggers, limit time spent walking through unmowed fields or areas with overgrown  vegetation.

If you do spend time in areas where chiggers are likely, wear clothing to cover as much of your skin as possible.  Insect repellents can help ward off chiggers.

After spending time outdoors, shower or bathe to remove any chiggers. Chiggers prefer to attach to areas of the body where the skin is thin, tender, or wrinkled, so be sure to wash thoroughly.  Don’t forget to wash your hair! Be sure to also launder any clothing items which may have been exposed to chiggers.

Chigger bites are very uncomfortable, with the most intense itching occurring about 24-48 hours after the initial bite.  Over-the-counter remedies including antihistamines and topical steroids can help with the discomfort. The welts formed in response to a chigger bite can last up to 2 weeks.  Avoid scratching, as it can break the skin and encourage bacterial infection.

Other Useful Information

  • Despite what you may have heard, chiggers do not burrow into the skin of their victims.  Consequently, coating chigger bites with nail polish will not smother the chiggers.  A common misconception is that the bright red spot in the center of the chigger bite is the mite itself.  The red spot is actually the stylostome, left behind by the chigger.
  • Chigger bites may cause some people to become allergic to meat.  This same allergy, called alpha-gal, has been demonstrated following tick bites.  


Where and When Are They Found?

Not only do mosquitoes cause itchy bites, they are considered the deadliest animals in the world
Mosquitoes are considered the deadliest animals in the world

There are more than 3,500  species of mosquitoes found world wide. They thrive in moist, warm, humid areas, breeding in damp soil or standing water.   

Only female mosquitoes bite, using blood proteins from host blood to develop eggs. During the lifetime of a female mosquito (typically 3-4 weeks), she can produce over 1,000 eggs.

You may not believe me, but mosquitoes are considered the most deadly animal in the world. Why? Mosquitoes are insect vectors for a host of diseases, including malaria, dengue, Eastern equine encephalitis, West Nile virus, Yellow Fever, Chikungunya, and Zika virus.  Malaria alone kills more than 400,000 people every year. Mosquitoes also transmit diseases to animals, including heartworm to dogs.

What Causes the Itch?

Like chiggers, female mosquitoes don’t technically bite.  Instead, they pierce the skin with a proboscis which sucks up blood like a straw.  Mosquito saliva contains an anesthetic to numb the victim’s skin as well as an anticoagulant to keep the blood from clotting.  The itchy bump associated with the bite is due to the inflammatory response directed at the mosquito saliva.

Prevention Tips and How to Find Relief

Do not let water stand anywhere outside your home, as it is a breeding ground for mosquitoes.  Often overlooked spots that may contain stagnant water are flower pots saucers, tarps, and areas surrounding air conditioner units. Water in outdoor pet dishes should be changed every 3-4 days, and in birdbaths and wading pools once a week.  

Mosquitoes bite most often at dawn and dusk, so avoid being outdoors during that time if possible, If you will be outside, wear long, lightweight clothing to protect your skin and use insect repellent.  If you do get bit, over-the-counter medicines are effective at relieving the itch.

Other Useful Information

  • Mosquitoes are able to detect the presence of animal hosts (including humans) by detecting the carbon dioxide we exhale.  
  • If you think that mosquitoes seem to like you more than others, you may be right.  Scientists have shown some individuals are more attractive to mosquitoes than others.  Why? The jury is still out on that one, but several factors are being considered. Mosquitoes may be more attracted to people with type O blood and to people with higher metabolism.  The genomic sequencing company 23andMe is actually trying to determine which gene sequences may predispose people to mosquito bites. Learn more (and watch a super cool mosquito experiment) by watching the following video. It’s a little long (a bit over 12 minutes) but it is fascinating!

Hopefully, you come away from this post with actionable steps you can take to limit your exposure to the itches of summer. I know that poison ivy/oak/sumac, chiggers, and mosquitoes won’t keep me from spending time outdoors enjoying the gifts of the season.

What are your go-to products for preventing or treating the itches of summer? Let me know in the comments.

Related Posts

How to Recognize Poison Ivy, Oak, & Sumac and Treat Their Rashes by Art of Manliness

How to Clear Poison Ivy by HowStuffWorks

How To Safely Remove Poison Ivy And Hemlock From Your Backyard

This May Be the Deadliest Creature on Earth by National Geographic

*The tricky thing is that different species of these plants live in different parts of the country.  In doing my research, I came across a very useful site (Poison-ivy.org). On it, you can find out the most common species of poison ivy, poison sumac, and poison oak in your particular area.  You can check out this great resource by clicking here.  

My thanks to Jonathan Sachs for granting me permission to use images from his site, Poison-ivy.org

Increased time spent out of doors can lead to exposure to one or more of the scourges of summer:  poison ivy, chiggers, and mosquitoes.   In this post, I explain the science behind the itches of summer, dispel some myths, and provide steps you can take to protect yourself this season.

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