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So I did a hike in a forest infested with leeches. I ended up with quite a few leech bites (around 20). But, at the same time, another hiker got just one bite!

We both were wearing similar shoes, socks and trek suits. Hence, in theory we were pretty similar. Also, we did clean up the shoes/socks often. Yet, the number of leeches on me was way more than the one on the other trekker.

So what is it that attracts the leeches? Do they have a preference of going for a particular set of people? (Maybe driven by smell?).

Charlie Brumbaugh
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Ricketyship
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1 Answers1

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Nah, AFAIK Leeches don't sniff/smell at all. Their main form of prey detection is thought to be by thermoreception, meaning Sensitivity to body heat, which is why warm blooded animals and mostly mammals are their preys. They do get attracted towards Water/Wetness. Though you are claiming to be having similar sort of a clothing, I believe you two must not have sweat in a similar amount. Leeches in India (where you trekked, I assume) are more of often found in Humid regions.

WedaPashi
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  • Now wait, what's the relation between amount of sweat and body heat? Because you mentioned that thermo-reception is the criteria and then you mentioned about sweating. – Ricketyship Nov 18 '13 at 15:10
  • @Unsung: Bingo! I always knew this will the point to be raised. See mate, when we trek in humid areas, (for an ideal example for which the weather and jungle part you can imagine: Jaigad in Konkan, if you have trekked), we normally sweat. The more humid is the weather, the more we sweat. This sweat part is Heat for us, leeches see it as wet. And when they actually come in contact with our skin, the head towards the heat. Had the leeches being targeting either the heat or wet, then cattles would never get leeches on them, yet they do! – WedaPashi Nov 18 '13 at 15:16
  • So leeches are attracted to wetness and heat both. And hence, when we sweat more, there are good chances that we will end up attracting leeches. Once they get on us, they find the heat source and go for it. Is my understanding right? – Ricketyship Nov 18 '13 at 16:08
  • @Unsung: Yes, you got it! – WedaPashi Nov 19 '13 at 06:10