Rengas-attack

Another itchy and sleep-less week, this time not of the ticks but the notorious Rengas, a plant in the mango family (Anacardiaceae). Urushiol, an oil found mainly in the Anacardiads, causes an allergic skin rash on contact. Unlucky ones, like me, have worse reaction. But some people are even sensitive enough to get allergic reaction just from eating mango!

Just by brushing against the leaves. As bad as tick bite, if you can imagine.

Urushiol-induced contact dermatitis

The name Rengas actually refers to trees in the genera Gluta and Semecarpus. Here I refer the name to Gluta wallichii (I have been using this name to curse, and it really sounds like bad words). The Wallich's Rengas is actually quite common in our forest, especially at BTNR (70 big trees recorded in my survey), and they can grow quite big (the biggest Rengas I recorded is 78cm in diameter). However, we normally came across (and "kissed" by) saplings of our height. It is not difficult to spot them. Just look out for "black spots" (dried sap), just like those on mango skin.

Leaves of a Rengas sapling, ca. 30cm long (smaller and stiffer in big trees).

Some vegetative characters to identify Rengas.

Rengas' bark fissures like Seraya, but normally scattered with its infamous tell tale sign. Don't anyhow hug a "Seraya" if you are not sure what it is!

It's rare to find them fruiting, like most other rainforest trees. But if you see something like this in the future, it could be Rengas fruit. Picture here is the Rengas-like fruit of Swintonia schwenkii, a cousin of Rengas. See here for a dried Rengas fruit taken by lekowala at BTNR.

It's my laziness (of not wearing long) to be blamed for my rash, not Rengas. After all, at least we can spot a Rengas and avoid it, can't do that on ticks.

No matter what, I still love mango and cashew nuts.

How big can a forest tick grow?

According to Wikipedia, ticks undergo a lifecycle of several stages. Those we encountered (and got bitten most of the time) are the nymphs (ca. 1-2mm) and some perhaps larvae. So, just how big can a forest tick grow? I was quite intrigued by this question as I never got bitten by an adult one before. Actually, I'd never want to be bitten by one as I can't imagine something as big as the adult dog ticks (ca. 5-8mm) I used to remove from my dogs crawling over and penetrate my skin - unthinkable!

I was lucky enough not to get bitten by any tick yesterday (even when I walked almost the whole reserve, as opposed to the day I last work there - only in a 20m x 20m area) yet caught an adult which was "trying to feed on my pants"!

As big as a dog tick, just flatter and more brownish. My poor North Face Paramount.

Tough sucker, won't let go easily and need to be removed carefully

This is why - barbs along the mouthpart!

Rather cute, actually. Now I decide to name it Pantsy (for simple reason).

On it's back and mummified. R.I.P., Pantsy. Never suck pants again in your next life.

tick-away

What a name to restart this blog in 2008. My time is really ticking - no manuscript (yet) after almost one year of the completion of Big Tree survey - everything has been just ticking along slowly (ticking over). I need to find the very thing that makes me tick and be productive. The eleventh hour gets a tick for that but it is also unhealthy.

Anyway, productivity aside, I was really ticked off by the way the forest welcomed me back - its very own TICKS, some 50 or so of them! These creatures, albeit tiny, gave me unforgettable love bites that make me wish that I can cut off my limbs! My body is so allergic to their saliva that I couldn't sleep for the past 10 days and need to be on both anti-histamine and steroid cream.

two days after bite, not showing those on arm, tight, hip, and parts rather not mention here

fourth day - one of the itchiest days (actually can't think of which day is not itchy)

day 11 - finally healing, with an accidental scratch scar

Fortunately unlike ticks in the temperate, these tropical ticks are unlikely to be vectors of diseases (e.g. Lyme disease). In every stage of their lifecycle, they just climb up a stem/grass and wait to attach to a passing host, and a meal of fresh blood. The only way to avoid getting their painful (itchy) bites is to avoid physical contact with the shrubs they perched on, or wear pesticide-treated clothes (and get some chronic poisoning at the same time).

I guess the moral of the story is not to walk into the forest if you do not need to (this goes to everyone, whether or not your favorite activity has to do with some letters 'H'). Hopefully ticks do safeguard the seedlings from some human trampling.

Myth or Truth: some people believe that ticks deposit eggs under host's skin when they bite, and the larvae will chomp away tissue after they're hatched, hence the unbearable itch. Think about this - if the ticks are able to inject eggs via their mouthpart (hypostome), they must have had their organs growing in their face, and they must be doing only "oral" sex.