effectiveness of Parsnip Webworms
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Frederick W. Schueler
Aug 13, 2024, 12:15:49 AMAug 13
to Eastern Ontario Natural History listserve
Everyone,
reporting on the conditions of Parsnips at the Healing Place last
fall, I concluded that "there's not a lot of web-worming of the Parsnip
- something like 2% or 12% of the plants in my two transects. Presumably
the thing that would be needed to increase the population would be to
provide conditions in which more adult moths can over-winter, but I
don't know if the 'sheltered place' (fide wikipedia) of over-wintering
has been studied."
I had thought that unmowed stands might be controlled by the webworms -
https://ngtimes.ca/does-mowing-down-the-golden-parsnips-sustain-them/ -
but now, seeing so many stands of Parsnips with so few Webworms, I think
we'll need to learn more about how to encourage over-wintering of the
moths before this can be the case.
Around our house we let the Parsnips grow freely, and while we don't
know what conditions would improve the over-wintering of the moths, we
keep the place sort of weedy and messy, i part hoping this will
encourage the moths to successfully overwinter, and then produce lots of
caterpillars to inhibit seeding by the Parsnips.
I've just done the third survey of the Webworms on the plants, and now
that most of them are going to seed, I've totaled up that there were 22
plants with Webworm webs, 8 without webs, and, if each plant is reckoned
equally, a 44% reduction in seed production. This isn't going to
eliminate the Parsnips, but if other forces were going to reduce their
population, this reduced seed production would certainly accelerate the
process.
fred.
==================================================
12 August 2024 - Canada: Ontario: Grenville County: Oxford-on-Rideau:
Bishops Mills:S side(Pipers House Garden). (30m garden), 44.87147° N
75.70045° W TIME: 1840-1848. AIR TEMP: 21°C, sunny, sunset, Beaufort
light breeze. HABITAT: untilled raised(heaped)garden bed, rural village,
shallow soil limestone plain. OBSERVER: Frederick W. Schueler.
2024/221/b, Pastinaca sativa (Parsnip) (Plant). common herb, in fruit,
prey of predator, seen. resurvey of Webworms on >1 m plants around
garden & surroundings. 22 plants with Depressaria pastinacella (Parsnip
Webworm) webs - 8 without webs - 44% reduction in seed production, if
each plant is reckoned equally.
#6 civic address sign: 5 plants, with no or minor webs, no seeding lost,
some in bloom.
Along concrete slab: Two tall plants 90% stripped of seed potential, 4
others 70% stripped. A Daucus carota (Carrot) plant on which small webs
had been formed a week or so ago does not have a caterpillar or webbing now.
Near water pump: The largest plant 90% intact, 4 others 60% stripped.
First blooming plant near the Rhubarb: No webbing on first-bloomer,
taller nearby plant 60% stripped.
Near new woodshed: Two tall plants 70% stripped, 2 1 m plants 90% intact.
Along the bean wire: 1 plant 50% stripped - surrounded by tall
Helianthus tuberosus (Jerusalem-artichoke) plants.
Along Ash Heaps: Big bent-down plant pretty well intact, 1 m plant in
bloom with no webs.
Around Firepit Pond: All bent down in the water, perhaps 50% stripped.
reporting on the conditions of Parsnips at the Healing Place last
fall, I concluded that "there's not a lot of web-worming of the Parsnip
- something like 2% or 12% of the plants in my two transects. Presumably
the thing that would be needed to increase the population would be to
provide conditions in which more adult moths can over-winter, but I
don't know if the 'sheltered place' (fide wikipedia) of over-wintering
has been studied."
I had thought that unmowed stands might be controlled by the webworms -
https://ngtimes.ca/does-mowing-down-the-golden-parsnips-sustain-them/ -
but now, seeing so many stands of Parsnips with so few Webworms, I think
we'll need to learn more about how to encourage over-wintering of the
moths before this can be the case.
Around our house we let the Parsnips grow freely, and while we don't
know what conditions would improve the over-wintering of the moths, we
keep the place sort of weedy and messy, i part hoping this will
encourage the moths to successfully overwinter, and then produce lots of
caterpillars to inhibit seeding by the Parsnips.
I've just done the third survey of the Webworms on the plants, and now
that most of them are going to seed, I've totaled up that there were 22
plants with Webworm webs, 8 without webs, and, if each plant is reckoned
equally, a 44% reduction in seed production. This isn't going to
eliminate the Parsnips, but if other forces were going to reduce their
population, this reduced seed production would certainly accelerate the
process.
fred.
==================================================
12 August 2024 - Canada: Ontario: Grenville County: Oxford-on-Rideau:
Bishops Mills:S side(Pipers House Garden). (30m garden), 44.87147° N
75.70045° W TIME: 1840-1848. AIR TEMP: 21°C, sunny, sunset, Beaufort
light breeze. HABITAT: untilled raised(heaped)garden bed, rural village,
shallow soil limestone plain. OBSERVER: Frederick W. Schueler.
2024/221/b, Pastinaca sativa (Parsnip) (Plant). common herb, in fruit,
prey of predator, seen. resurvey of Webworms on >1 m plants around
garden & surroundings. 22 plants with Depressaria pastinacella (Parsnip
Webworm) webs - 8 without webs - 44% reduction in seed production, if
each plant is reckoned equally.
#6 civic address sign: 5 plants, with no or minor webs, no seeding lost,
some in bloom.
Along concrete slab: Two tall plants 90% stripped of seed potential, 4
others 70% stripped. A Daucus carota (Carrot) plant on which small webs
had been formed a week or so ago does not have a caterpillar or webbing now.
Near water pump: The largest plant 90% intact, 4 others 60% stripped.
First blooming plant near the Rhubarb: No webbing on first-bloomer,
taller nearby plant 60% stripped.
Near new woodshed: Two tall plants 70% stripped, 2 1 m plants 90% intact.
Along the bean wire: 1 plant 50% stripped - surrounded by tall
Helianthus tuberosus (Jerusalem-artichoke) plants.
Along Ash Heaps: Big bent-down plant pretty well intact, 1 m plant in
bloom with no webs.
Around Firepit Pond: All bent down in the water, perhaps 50% stripped.
rmb...@istar.ca
Aug 13, 2024, 7:59:21 AMAug 13
to natur...@googlegroups.com
Quick question: are the parsnips annuals or perrenials? Fortunately
I don't have any on my property...yet. In fact I haven't seen any
nearby but have been told they're on the sides of the Cataraqui Trail.
I have enough challenges with the stupid swallowwort vines that are
spreading.
Rose-Marie, north of Perth Road Village
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Frederick W. Schueler
Aug 13, 2024, 8:09:47 AMAug 13
to natur...@googlegroups.com
On 13-Aug-24 7:59 a.m., rmb...@istar.ca wrote:
>
> Quick question: are the parsnips annuals or perrenials? Fortunately I
> don't have any on my property...yet. In fact I haven't seen any nearby
> but have been told they're on the sides of the Cataraqui Trail. I have
> enough challenges with the stupid swallowwort vines that are spreading.
* Parsnips are biennials - the first year they grow the
>
> Quick question: are the parsnips annuals or perrenials? Fortunately I
> don't have any on my property...yet. In fact I haven't seen any nearby
> but have been told they're on the sides of the Cataraqui Trail. I have
> enough challenges with the stupid swallowwort vines that are spreading.
vegetable-parsnip root, and then in the second year a stalk with umbels
of tiny yellow flowers, which grow into flat seeds, and then the plant dies.
They tend to be much less abundant on the Shield than on limestone areas.
fred.
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