Trekking off the beaten track

Make sure you are protected from Malaria and you must take a good supply of insect repellent

We will. Thanks for the tip

Here's an article about a natural insect repellent developed by high school students

Also, I use Tea Tree oil to treat some skin conditions, and I've noticed the bugs stay away for a while after freshly applied using a fragrance-free lotion 'carrier'.

It's probably not acting so much as a repellent as it may be masking my deliciousness...

Those Viet kids are obviously clever and very resourceful. I hope their repellent replaces DEET, which I consider to be obnoxious and poisonous. Viet kids are so bright and attentive.  They will be a pure joy to teach.

BTW, a group of engineers has developed a laser system that can shoot mosquitos out of the air. It can even be programmed to kill only the females (the biters) by counting wingbeats-per-second. The males and females are different in that respect.

The ingredients the high school students used are some of the ingredients I've been using in my own blend for insect repellent for years. 

I mixed lemon eucalyptus (recommended by the CDC and not the same as lemon or eucalyptus), lemon balm, lavender, citronella, peppermint, thyme, tea tree, orange, grapefruit, and catnip, together with a carrier oil (I used either jojoba or almond) in a small bottle that I've kept it in my bag at all time.  I didn't use alcohol, however.  Alcohol would defeat the purpose of a natural product, and I've been trying very hard not to have chemical on or in my body for a couple of decades now.

Ciambella wrote:

The ingredients the high school students used are some of the ingredients I've been using in my own blend for insect repellent for years. 

I mixed lemon eucalyptus (recommended by the CDC and not the same as lemon or eucalyptus), lemon balm, lavender, citronella, peppermint, thyme, tea tree, orange, grapefruit, and catnip, together with a carrier oil (I used either jojoba or almond) in a small bottle that I've kept it in my bag at all time.  I didn't use alcohol, however.  Alcohol would defeat the purpose of a natural product, and I've been trying very hard not to have chemical on or in my body for a couple of decades now.

As I read the article, my impression was that the alcohol is used as a means to extract the essential elements. I'm probably wrong.

It's essentially a human interest story so some technical details about the full process were likely left in the editor's recycle folder.

Would alcohol be left to evaporate, leaving behind the essentials, alcohol free?

A water & ethanol mix is called an azeotropic solution which makes it very difficult to remove the last 5% of the ethanol. Water and ethanol have a great affinity for each other. But if the ethanol is that much of a problem then other solvents can be used. Even steam can be used to extract essential oils. Other solvents can also be used such as acetone, methanol, ether, CO2, and even butane if you  have a system that can work at higher pressures.
I wouldn't be worried about ethanol because the repellent was being used on structures and would evaporate rapidly - both the ethanol and the water. If the repellent was sprayed on clothing and allowed to dry before wearing, both the water and the ethanol would go away.
Ethanol would be my choice because it is such a good, low toxicity solvent. It is very easy to use. Google soxhlet extractor.

Jim-Minh wrote:

Viet kids are so bright and attentive.  They will be a pure joy to teach.

Don't fool yourself.  I have taught in both the US and Vietnam, middle-schoolers in particular.  That is the age that many teachers refuse to work with.  I can tell you that just like anywhere else, there are the ones that are a joy to teach and there are those that are nothing but a royal pain in the the butt.  They are the same as kids anywhere.

BTW I have also taught Japanese visiting students in Honolulu and they are so polite that after a while it gets a little boring.

Ditto.  My experience was with Vietnamese 8th graders (public school) and 11th graders (private school) during the early and mid 1970s, American 7th graders (public school) during the  early 1980s, and Italian 7th and 8th graders (public school) during the early and mid 2000s.  It's amazing that the same attitude can be found in different continents, different culture, and different socioeconomic circles.

Japanese children (and Japanese people in general) are an exception, I've heard.

Puberty messes with their minds, same of course in every country. (More proof that Japan is populated by space aliens.)

Even in the animal kingdom. I had big families of raccoons visit for cat food snacks. The adults and babies were fine, jeez the teenagers were terror. (still fun to watch!)

MathewP wrote:

A local motivated guide is a plus .....

I would say that a local guide is more than a plus, he is a necessity.  In the highland areas, both north and south, there are extensive military exercise areas that are strictly off-limits to all.  Locals could get in trouble for entering these areas.  You could be deported.  The boundaries may not all be well marked especially if you are traveling on foot.  Of course how to tell the difference between a knowledgeable guide and one who just says he is, that's another story.

THIGV wrote:

MathewP wrote:

A local motivated guide is a plus .....

I would say that a local guide is more than a plus, he is a necessity.  In the highland areas, both north and south, there are extensive military exercise areas that are strictly off-limits to all.  Locals could get in trouble for entering these areas.  You could be deported.  The boundaries may not all be well marked especially if you are traveling on foot.  Of course how to tell the difference between a knowledgeable guide and one who just says he is, that's another story.

I planned to go camping and hiking in the area around Da Lat. To get deported for wandering into a restricted area would be the ultimate bummer. Thanks muchly - I'll find a local guide to help me keep out of trouble.

MMS:>  Miracle Mineral Solution < that's all you need > https://www.scribd.com/document/1301310 … isease-pdf < do your own resurch before you go this product is very cheap and works ... will cover you for most things
2 travel bottles is more then you will need ( .........

MMS stands for
“
Miracle Mineral Solution
”
, the namewas given to the solution by an American scientist, JimHumble, who discovered its phenomenal anti-parasiticeffect while using it to disinfect water. To make the storyshort, Humble was with colleagues in the jungle doing amining research, two of his friends got unexpectedMalaria and got really bad fast. Having advancedsymptoms and being days away from any civilizedlocation, he suggested giving them a dose of his waterpurification drops and they agreed. Four hours later theywere up and laughing about how bad they felt few hoursago, and the next day they were back working as if nothing happened. Since the time, Humble treatedhundreds of thousands of people for Malaria and otherparasitic ailments of all sorts, spending most of his time inless fortunate villages where treatment was most needed,
this didn’t however stand in the way of MMS’s reputation
booming all over the internet and the world.

OP,

Something I saw in a travel blog yesterday: be careful about hiking too close to borders. Apparently it's too easy to appear suspicious to the government in those areas.