Thread: Insects
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Old 2020-09-08, 12:23   #26
Dr Sardonicus
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Feb 2017

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Yes, the Black Swallowtail Papilio polyxenes is a likely suspect:
Other Common Names
Eastern Black Swallowtail
Parsely Swallowtail
Dill Worm, Parsley Worm, Celery Worm
Carrot Worm, Fennel Worm

Explanation of Names
Papilio polyxenes Fabricius, 1775
The common names for the caterpillars vary because they can be found on many important cultivated plants in the Carrot Family. Pick the host plant, add the word "worm", and you have another common name that has probably been used and published somewhere.
This page has a number of good images of the caterpillars; click on an image to enlarge.

Like most swallowtail caterpillars, they have a "bison-shouldered" appearance, and have a pair of "horns" that are normally retracted, but which will protrude and emit a bad smell if the caterpillar is disturbed. (Many swallowtail caterpillars have large eye spots on the "shoulder hump," but these do not.)

As to the aphids: My milkweed got heavily infested with dark aphids this year. They went to the tender young growth at the ends. I didn't want to use insecticidal soap for fear of harming the Monarch caterpillars so I picked off the ends -- aphids, "farmer" ants, and all. This controlled the problem, and in later days I saw ladybugs munching their way through the aphids. BTW I remember wondering as a kid what those black-and-orange things were that looked like little 6-legged lizards. They're ladybug larvae! And they chow down on aphids even faster than the adults.

Last year my milkweed got hit by swarms of horrible bright-orange aphids, a type I'd never seen before. I looked them up and found they were Oleander aphids, Aphis nerii. They think they're better than ordinary aphids because they're imported. When feeding on milkweed they accumulate the plant's toxins, and this prevents ladybug and lacewing larvae that eat them from maturing. One control method I read was to dab them with a swab soaked in rubbing alcohol. Rubbing alcohol has been in short supply because of COVID-19, so I feel fortunate that I haven't been bothered with these appalling pests so far this year. I have seen them in the area, though.
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