My
wife, Katie, went out to pick some lettuce from her porch garden box, when she
saw these two guys having a garden party and chowing down on her parsley! But just who were they?
Turns
out they are known as parsley caterpillars or parsley worms, and they turn into
beautiful butterflies called eastern black swallowtails
(papilio polyxenes), which are found from southern Canada to northern
South America but are most common east of the Rocky Mountains.
The
caterpillars enjoy feeding on members of the carrot family (apiaceae),
such as dill, parsley, fennel, celery, caraway, and carrot are common food
sources in backyard gardens. Wild plants
that eastern black swallowtail caterpillars also eat non-native plants like queen
anne’s lace (wild carrot, daucus carota), poison hemlock (conium
maculatum), and wild parsnip (pastinaca sativa), as well as native plants
such as golden alexander (zizia aurea) and spotted water hemlock (cicuta
maculata).
Female
black swallowtails lay round, pale yellow eggs, individually on host plants,
usually on new leaves but occasionally on flowers. The eggs darken as the caterpillar grows inside
and hatch in 3 to 9 days, when the worm chews its way out of the egg and eats
the eggshell.
The
first caterpillar instars are mostly black and spiny, with a whitish spot, and
look like bird droppings. The second and
third instars have spines that are reddish orange, and the fourth and fifth
instars are green with transverse bands of black and yellow, a camouflage
pattern that makes them hard to see while resting on the sun-speckled plants. The caterpillars
grow to be 1½ to 2 inches (4 to 5 cm) long and the caterpillar stage takes 10
to 30 days, depending on outside temperature and the type of plant that the
caterpillar is living on.
All
swallowtail caterpillars have a reversible horn-like organ behind the head
known as an osmeterium which looks like a forked snake’s tongue. On the parsley worm it is a bright yellowish-orange
color and if it is disturbed the caterpillar will rear up, extend its
osmeterium, and release a foul smelling chemical repellent to repel predators.
Once
the fifth instar caterpillar matures, it leaves the host plant to find a place
to pupate and build a chrysalis. A swallowtail
caterpillar normally positions itself “heads-up” on a plant stem, tree
trunk, or a foundation wall and spinning a slender silken band to support
itself and attaching its back end to a silk pad. It then molts one final time to form a
chrysalis with short horn-like protrusions where its head is. The color of the chrysalis is either greenish
with yellow markings or mottled brown. This
is determined not by the individual’s immediate surroundings, but genetically;
overwintering pupae are always brownish.
Adult eastern black swallowtails’ wings are black with yellow, blue, orange and red markings, with two rows of yellow spots along theedges, and a powdery iridescent blue area between the two rows and a red eyespot on the edge of each wing, near the narrow tail.
Eastern
black swallowtails are sexually dimorphic, and the females are larger than the
males, with a wingspan of 3¼ to 4¼ inches.
You can tell males from females, because the males have larger and
brighter yellow spots than the females, while the females have smaller and
lighter colored yellow spots and brighter blue areas.
Eastern
black swallowtail butterflies drink nectar from
milkweed, thistles, purple coneflower, zinnias, and many other flowers.
So,
it is okay if these guys come to the garden party, as long as they don’t bring
too many friends, because they will turn into beautiful butterflies!
I
hope that you continue to enjoy The Woodsman’s Journal Online and look for me
on YouTube at BandanaMan Productions for other related videos, HERE. Don’t forget to follow me on both The
Woodsman’s Journal Online, HERE,
and subscribe to BandanaMan Productions on YouTube. If you have questions, as always, feel free
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That
is all for now, and as always, until next time, Happy Trails!
Sources
Bonelli,
Paula; “Parsley Caterpillar: Garden Friend or Foe?”, Birds & Blooms, July
29, 2021, [© 2024 RDA Enthusiast Brands, LLC], https://www.birdsandblooms.com/gardening/attracting-butterflies/parsley-caterpillar/,
accessed August 23, 2024
University
of Wisconsin; “Black swallowtail, Papilio polyxenes”, [© 2024 The Board of
Regents of the University of Wisconsin System], https://hort.extension.wisc.edu/articles/black-swallowtail-papilio-polyxenes/#:~:text=The%20yellow%20spots%20are%20typically,difference%20is%20called%20sexual%20dimorphism,
accessed August 23, 2024
Wikimedia; “Male black
swallowtail butterfly on wild bergamot at Sherburne National Wildlife Refuge in
Minnesota”, by Kris Spaeth/USFWS, July 12, 2016, https://commons.wikimedia.org/wiki/File:Black_Swallowtail_Butterfly_(28283722255).jpg,
accessed August 23, 2024
Wikimedia; “Black
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accessed August 23, 2024
Wikimedia; “A Black
Swallowtail butterfly”, August 6, 2007, by Kenneth Dwain Harrelson, https://commons.wikimedia.org/wiki/File:Pristine_Black_Swallowtail.jpg,
accessed August 23, 2024
Wikimedia; “Papilio
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accessed August 23, 2024
Wikimedia; “The chrysalis
of the black swallowtail butterfly, Papilio polyxenes. Gray/brown color morph. Image taken in Pittsburgh, Pennsylvania at
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accessed August 23, 2024
Wikimedia; “Black
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accessed August 23, 2024