Author Archives: Colin Purrington

About Colin Purrington

PhD in evolutionary biology • twitterinstagram

Shaving your legs to deter ticks

Colin Purrington Photography: Green steps &emdash; girl-with-shaved-legsPeople shave their legs for a variety of reasons: to look younger (artificial neoteny), to look less like men, to show off tattoos, to show off muscle definition, to improve athletic performance (less drag, plus fools brain into thinking you’re going fast), to facilitate post-accident wound cleaning (cyclists), and because shaved legs induces a pleasurable sensory overload (at least to some). But can shaving also protect you from ticks? I became curious this week after watching a tick crawl up my leg (photograph below). I was really surprised to discover that no experiments on this topic have been done, but did succeed in finding three relevant snippets on the internet (two from mountain bikers, one from cross country runner):

“One thing that helps is shaving your legs. Not a foolproof way but I would say it reduces them critters by 80%, maybe more. I noticed that when my wife and I were out and she had none, I had around 14 that day.” source

“As an experiment I shaved my legs before riding point to point at lbl with KRS and a few others. It was tick season. After 40+ miles of riding I had 1 tick on my sock. Along the way KRS pulled OVER 15 ticks. We rode the same route at the same pace. I’ve kept the hair off ever since.”  source

“I’d say its mostly impractical. Although, I know many trail runners (including myself sometimes in the summer) do it to prevent ticks from attaching.” source

But, hey, maybe the anecdotes are just that, and hairy legs actually deter ticks in some way. 

Colin Purrington Photography: Spiders and ticks &emdash; American dog tick (Dermacentor variabilis)

But it makes sense that shaving would deter ticks. The first is obvious: ticks can grip hair, so if you are hairless (and are wearing shorts, skirt, or kilt), they can’t climb as fast (they are headed for your groin, by the way). The second is that you if you have hairless legs you can most likely better feel them crawling up your legs. I.e., all eight of their legs are touching your skin’s sensory array (or all six of their legs if they are larvae). The third is that when you remove all your leg hair you are removing a lot of sensory distractions caused by wind (experiment on swimmers), and thus you can zero in on things crawling on you. Indeed, all of these mechanisms might touch on why we evolved to be relatively hairless in the first place

So about the experiments that need to be done …

An easy way to assess would be to count numbers of ticks on a group of people out for a walk, some of whom shave. But at least in the United States, that would break down to men versus women, and males smell worse than women and thus might attract more ticks, regardless of hirsuteness. And men are usually larger, so there’s the surface area thing that goes against us, too. So it would be far better to recruit a group of hairy-legged women and ask them to shave just one leg, then march around a field known to have ticks. Participants would tie white bandanas around their upper thighs to arrest the ticks before they got too intimate, then count tick numbers. But finding enough women who don’t shave might make the protocol hard to follow (again, at least in the United States). So perhaps using a group of guys would be more feasible. An ideal group might be a men’s college swim team right before the season begins. Just ask the coach to donate their legs for science. Would be an easy publication for a day’s work, and the experiment would be crazy photogenic. Plus great team-building exercise. Would get the college on the evening news I’m sure. 

A simpler design might be to just have a motivated group of people (perhaps students in a field ecology course?) conduct tick races on shaved, unshaved legs. You just need to start them on the ankles and have participants hold still while the ticks make their ascents. That would be equally photogenic and fun, I think. And to get at the perception part, you could have blindfolded participants that would be asked to identify location of ticks crawling up legs (with controls being placement of non-ticks on ankles, perhaps).

The proposed experiments might seem horrific, but just the for record, I once swam around the edges of a small pond just to see how many leeches would attach to me. I recall that my father challenged me, and that we were going to see who could win. I don’t remember who ended up with more. (Yes, that was a nerd x testosterone interaction effect.)

If somebody does go ahead and conducts this experiment — and if the effect is huge (my guess) — the next step would be to alert the folks at the CDC so they could add a shaving recommendation to their tick page. The reaction to that would be entertaining.

Posted in Biology, Education, Gardening, Photography, Science | Tagged , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

Golden-backed snipe fly

Here’s a male golden-backed snipe fly (Chrysopilus thoracicus). The species is strangely understudied. For example, the adults don’t seem to feed, or at least do so very rarely or in complete privacy. I’ve read about them eating aphids, but that’s secondhand at best. The family (Rhagionidae) is full of predaceous members, so it’s certainly possible, but it’s still odd that we don’t really know for sure, and there should be at least a single photograph of them eating something. I wish somebody would PCR their gut contents to settle the issue. Not much is known about the larvae (image), either, other than that they can mature in rotting logs (Johnson 1912). 

Colin Purrington Photography: Insects &emdash; Male Chrysopilus thoracicus on leaf

I’ve photographed this insect twice before. One was floating on top of water, the other was sporting a severely dented eye. They are easy to photograph because they refuse to budge even when the lens gets within centimeters.

 Colin Purrington Photography: Insects &emdash; Golden-backed snipe fly (Chrysopilus thoracicus)

Colin Purrington Photography: Insects &emdash; Golden-backed snipe fly (Chrysopilus thoracicus) with dented eye

Snipe flies (Rhagionidae) are so named because their unfurled probosces resemble snipes (long-beaked birds in the Scolopacidae). Not everyone buys that naming explanation, though. Some insist it’s because of their agile, predaceous habit (i.e., they are good at sniping).

Posted in Biology, Photography, Science | Tagged , , , , , , , , | 1 Comment

Conference poster full of tips for creating conference posters

In case you need a quick guide to making a conference poster, here are two versions of my poster of poster tips. They have content overlap, so just choose the layout that pleases you. More details below the images.

Poster example (Colin Purrington's)Advice on designing scientific posters

Both posters are descendants of a document I created circa 1997 for my evolution students at Swarthmore College. The bottom one is available as a PDF if you want to print an actual poster of it — which I highly recommend if you are assigning a poster project for your class (students don’t like reading the website, below).

My full tips are at Designing conference posters. I created the website for my students, too, but eventually made it public in case it might help make the world’s poster sessions more enjoyable and their posters easier to understand. Please share with your friends.

Posted in Education, Science | Tagged , , , , , , , , , , , , , , , | 4 Comments

Toothed fungus

Toothed fungus emerging from a dead tree in late winter. I really enjoy a tiny fungus that’s just getting started because you can see the small details that are lost in photographs of larger specimens. For this one, it’s all about those yellow-tipped teeth and the translucent, waxy margins. It was growing on a log with hundreds of small, dried brackets so perhaps it’s Steccherinum ochraceum just getting started. But the margins are waxy, not fluffy, so Basidioradulum radula (Schizoporaceae) and Mycoacia fuscoatra (Meruliaceae) might be better ID. Finally, Radulomyces molaris (Pterulaceae) looks similar. And I’m sure there are dozens of other possibilities— there are several million species of fungi.

Colin Purrington Photography: Fungi &emdash; Toothed crust fungus in a bark cave

The above illustrates the flip side of photographing cute, immature fungi … they are hard to ID, especially if you don’t know much about fungi. I’ll have to go back in a few weeks to see what it looks like after some warmer weather. Without spores to examine for shape and size it might be hard to decide, so I really need to invest in a microscope. If you have an opinion on the ID, please leave a comment — I’d be grateful for any tips, even if it’s just a recommendation on a guide book for a newbie.

Colin Purrington Photography: Fungi &emdash; Toothed crust fungus in a bark cave

In trying to learn more about these species, I was struck by how ignored crust fungi are by mycologists and how they are left out of most field guides. The only interesting thing I could find was an article by Dimitrios Floudas lamenting this obscurity:

“The feeling of collecting these fungi is rewarding, but the frequent lack of people to share this excitement is discouraging.” 

Wise words for many taxa, I think.

Here’s a nice guide if you find yourself with an unidentified crust. You never know when that’s going to happen. 

Posted in Biology, Photography | Tagged , , , , , , , , , , , , , , , , , , , , | Leave a comment

Pyractomena borealis mouthparts

Here are four anterior close-ups Pyractomena borealis. The telescoping head allows the larva to inject (via curved, hollow mandibles) a numbing agent into snails that have retreated inside their shells. The antennae and maxillae are also partially retractable. When a larva is done feeding on a snail (or slug or earthworm) it will de-slime all of these parts with the hooked, fingerlike projections of the holdfast organ (pygopod) located on the last abdominal segment. The head is also fully retractible (see previous post). These larvae are extremely active, so really hard to photograph.

 Colin Purrington Photography: Insects &emdash; Pyractomena borealis mouthparts

 Colin Purrington Photography: Insects &emdash; Pyractomena borealis mouthparts

Colin Purrington Photography: Insects &emdash; Pyractomena borealis mouthparts

Colin Purrington Photography: Insects &emdash; Pyractomena borealis mouthparts

Posted in Biology, Photography | Tagged , , , , , , , , , , , , , , , | Leave a comment