Tag Archives: sphingidae

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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Hummingbird and snowberry clearwing moths

Here are some photographs of the hummingbird clearwing moth (Hemaris thysbe) and the snowberry clearwing moth (H. diffinis).

Colin Purrington Photography: Insects &emdash; Hummingbird and snowberry clearwing moths

Day-active, colorful moths are rare enough, but these take it to the next level in their uncanny mimicry of hummingbirds and bumblebees, respectively. The mimicry presumably protects them from being eaten by predators such as crab spiders, praying mantids, and birds. In addition to the obvious behavioral and morphological resemblance to hummingbirds and bumblebees, the moths also make a slight humming noise that completes the disguise. The noise could easily be an unavoidable consequence of hovering flight (approximately 30 beats/second), but I wouldn’t be at all surprised if their wings are rigged in some way to exaggerate the noise. I’d love to know the answer to that. My other burning question is why the hummingbird clearwing moth has clear wings at all … I would expect selection to favor individuals that did not lose scales, because such a mutant would more resemble a hummingbird, which has opaque wings. I’m guessing that reason is not because fully-scaled wings are too heavy — the hummingbird hawk moth (Macroglossum stellatarum) in the Old World has opaque wings and can manage 70-90 beats/second (wow). I wonder whether a fully scaled wing might damp the humming sound. All photographs were taken at Natural Lands Trust’s Hildacy Farm Preserve in Media, Pennsylvania. Oh, and happy National Moth Week.

Colin Purrington Photography: Insects &emdash; Hummingbird clearwing moth (Hemaris thysbe) with unfurling proboscis

Colin Purrington Photography: Insects &emdash; Hummingbird clearwing moth (Hemaris thysbe) showing wing veination

Colin Purrington Photography: Insects &emdash; Hummingbird clearwing moth (Hemaris thysbe) nectaring

Colin Purrington Photography: Insects &emdash; Hummingbird clearwing moth (Hemaris thysbe) nectaring at wild bergamot

Colin Purrington Photography: Insects &emdash; Hummingbird clearwing moth (Hemaris thysbe) nectaring at wild bergamot

Colin Purrington Photography: Insects &emdash; Hummingbird clearwing moth (Hemaris thysbe) arriving at flower

Colin Purrington Photography: Insects &emdash; Hummingbird clearwing moth (Hemaris thysbe) nectaring at wild bergamot

Colin Purrington Photography: Insects &emdash; Snowberry clearwing moth (Hemaris diffinis)

Colin Purrington Photography: Insects &emdash; Snowberry clearwing moth (Hemaris diffinis)

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