Category Archives: Gardening

White-footed woods mosquito drinking nectar

Here’s a female white-footed mosquito (Psorophora ferox) that I photographed at the John Heinz National Wildlife Refuge in Tinicum, Pennsylvania. I’m not a mosquito expert, so my ID is a guess based on its green eyes and purple coloration. That’s a terrible way to identify a mosquito, I’m sure. It’s a female because the antennae are not especially fluffy Males have massive, bushy antennae for sensing the wingbeat noise that females make, which is at a higher frequency than that of males. I’m posting this photograph because it’s National Pollinator Week and few people appreciate the pollination that mosquitoes perform. But we could kill them all and we’d be fine, I’m sure.

Colin Purrington Photography: Insects &emdash; White-footed woods mosquito (Psorophora ferox) nectaring on goldenrod

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Using mosquitoes’ sweet tooth to control Zika transmission

Now that everyone wants to kill mosquitoes that transmit Zika virus, can somebody please make a transgenic plant that expresses mosquitocidal Bti (Bacillus thuringiensis subsp. israelensis) toxins? Just stick the Bti gene behind a phloem-specific promoter so that the protein gets pumped into the nectar. Then when males and female mosquitoes drink (and almost all do), they die. You could then plant acres of the modified plant nearby towns to protect people from Zika (and anything else transmitted by mosquitoes). The beauty of this method is that you could reduce populations of mosquitoes from an area without spraying, and do so for generations if you modified nectar-producing perennials. I know it’s trendy to dislike GMOs (like vaccines), but I think many people would support them under these circumstances.

And yes, apparently Bti toxins can kill adult mosquitoes (including Aedes aegypti), not just larvae. Klowden and Bulla 1984 demonstrated it, for example. And yes, Aedes aegypti drinks nectar (and probably fruit juice).

Of course, even if somebody had the incentive to make such a plant, it could take a decade to wade through the red tape involved in getting non-regulated status from governments. So if you want to do something today, leave out containers of sugar water (10%) that is laced with Bti (e.g., Mosquito Dunks, which you can buy online or at hardware stores). Maybe add something floral to attract them, too. (A review of olfactory cues suggests that imitation cherry and apple can work. If you don’t have those sitting around, I’d wager a few drops of jasmine flavoring or rose water would work, and those are easily found at local stores.) Even if the Bti doesn’t immediately kill the adult, adults sucking up a big sugar meal can transfer the bacteria to water where they lay eggs, and thus eventually cause the death of any larvae that develop. Note that bees and ants might get interested in your sugar water, but the Bti is completely harmless to them.

And if you don’t want to use Bti, there are plenty of articles on using sugar baits laced with insecticides (e.g., Qualis et al. 2013, Junilla et al. 2015). They really can work: mosquitoes absolutely love sugar and will drink up poisons in the process. These are great if you don’t want to use crop dusters to destroy all insects in the area.

If you have kids and want to entertain them, add food dyes to the sugar bait and then challenge them to find mosquitoes with bellies full of sugar water. For older kids that might be amused by actual science, use two dyes to test attractiveness of two different volatiles (or different sugars). It’s probably rare to recapture one right after a nectar meal, but when distended they reveal gut contents nicely.

Colin Purrington Photography: Insects &emdash; White-footed woods mosquito (Psorophora ferox) nectaring on goldenrod

FYI, the photograph above is a white-footed woods mosquito (Psorophora ferox), not Aedes aegypti. It doesn’t transmit Zika, but illustrates to the unbelieving that mosquitoes drink nectar. 

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Mountain laurel flowering in December

I stumbled upon a solitary mountain laurel (Kalmia latifolia) flower yesterday while walking around Lake Mohonk in New Paltz. It isn’t the prettiest mountain laurel flower, but it was DECEMBER 27th, approximately six (!) months before one would expect a mountain laurel flower in this area. This December has been the warmest on record for the area, I think, and Christmas Eve was almost 70 °F (!!). Crazy, and really, really sad. This flower isn’t alone, apparently — the New York Times has a compilation of strange phenology across the country.

Colin Purrington Photography: Plants &emdash; winter-mountain-laurel

If you’d like to see photographs of prettier mountain laurel at Mohonk, here are photographs I took a few summers ago.

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Sweet Potato Awareness Month

November is Sweet Potato Awareness Month (SPAM), and I do my part by reminding people that yams are something else entirely. As a foodie and an evolutionary biologist, I feel obliged to be a nudge about this. So here are three images to help.

First, a photograph of a white yam (Ipomoea rotunda) in a bin of sweet potatoes.

Colin Purrington Photography: Blog photos &emdash; A white yam (Dioscorea rotundata) in a bin of sweet potatoes (Ipomoea batatas)

Second, a photograph of three cultivars of sweet potato (all Ipomoea batatas) next to a yellow yam (Dioscorea cayennensis).

Photograph of sweet potatoes and yam

Third, an illustration of how yams and sweet potato are related (they aren’t). As a bonus, I’ve also indicated the position of potato.

yams-and-sweet-potatoes-difference

Please share this page with your family prior to Thanksgiving dinner. It will be one less thing to bicker about. If you need more details, here’s my “Yams versus sweet potatoes” page. Read it if you want to know why the slave trade caused the whole “yam” confusion problem.

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Distinguishing tobacco and tomato hornworm caterpillars

After agonizing over the identification of hornworm larvae for years, I’ve developed two tricks that I’d like to share. Tobacco hornworm (Manduca sexta) caterpillars have stripes (seven of them), so remember that by thinking of Lucky Strikes cigarettes. Horn is usually red or red-tipped, like a cigarette. Also, tobacco gives you dark teeth and lungs … and tobacco hornworms have black shadows on their stripes. Tomato hornworms (Manduca quinquemaculata) have eight chevrons (Vs), which you can remember by thinking of V8 juice, which is primarily tomato juice. Here’s the graphic you can share with friends who might have it wrong:

Photographs of tobacco and tomato hornworm caterpillars

If you can, please spread the word … most of the tens of thousands of tobacco hornworm photographs on the internet are misidentified as tomato hornworms. Even Wikipedia page for tomato hornworm shows tobacco hornworm larvae (I’m working on it …). The problem is that tobacco hornworm eats tomatoes, and people with fancy cameras grow a lot of tomatoes.

For people living in Hawaii, please note that the above doesn’t include Manduca blackburni, which is closely related to tomato hornworm.

Photograph of tomato hornworm from Amanda Hill.

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