Cutworms and bulbs

Mike Rummerfield mikerumm@gmail.com
Sat, 26 Mar 2016 20:23:44 PDT
Jean,
Thank you very much for providing the very detailed info and pertinent
links.  It will definitely help with id.

Regards,
Mike


On Fri, Mar 25, 2016 at 10:35 PM, <gardenpt@aol.com> wrote:

> Jane,
>
> Most likely the troublesome cutworms at your place are Noctua pronuba
> which go by various common names, among them greater yellow underwing,large
> yellow underwing, and the winter cutworm.
>
> This page shows the adult  and displays the seasonality in the northwest.
> The bright orange of the hind wings is easily recognized when the moth
> suddenly flies out its daytime hiding place, commonly a clumping perennial
> or small shrub.  Noctua comes is quite similar as an adult but the
> caterpillar is quite different than that of N. pronuba.)
>
> http://pnwmoths.biol.wwu.edu/browse/…
>
> The winter cutworm arrived in the northwest approx the year 2000. They
> overwinter as caterpillars. They typically feed at night during the fall,
> winter, and spring when temperatures are in the 40s or above. Thus, their
> damage is often attributed to slugs. You can differentiate the damage of
> these two pests by closely examining the edges of the holes in the leaves.
> Here, they specialized on my Pacific Coast iris hybrids, but they will also
> damage numerous other perennials, among them rhubarb leaves.
>
> This pub has excellent images which will help you ID the larvae.
> http://pestid.msu.edu/insects-and-arthropods/…
>
> As does this:
>
> https://ag.ndsu.edu/archive/entomology/…
>
>
> Also see bugguide:
> http://bugguide.net/node/view/9821/
>
> Least-toxic management includes various techniques and, as you've
> commented, some make sense for individual pots/small plantings, others
> don't:
> - row covers
> - handpicking (at night, about 10:30 or so) then snip in half or put into
> soapy water
>
>  - Btk (Bacillus thuringiensis kurstaki), which is specific to
> caterpillars, but is effective only when they are half-grown or younger.
> Mature specimens may be 2..5 inches long.
> Btk is available under several product names, among them Dipel, Thuricide,
> Caterpillar Killer, and more. (I suspect the cats are too old for this to
> be effective at this time; they will soon pupate and the moths will emerge
> in May.)
>
>
> Hope this helps,
> Jean
> from Portland,Oregon
>
>
> -----Original Message-----
> From: Jane McGary <janemcgary@earthlink.net>
> To: Pacific Bulb Society <pbs@lists.ibiblio.org>
> Sent: Sun, Mar 20, 2016 4:37 pm
> Subject: Re: [pbs] Cutworms and bulbs
>
>
>
> On 3/20/2016 3:37 PM, Diane Whitehead wrote:
> > When do these moths lay their eggs?  Maybe some nets or screens could
> keep them out of your greenhouse.
> >
> >
>
> I should have mentioned that the "greenhouse" is 20 by 40 feet and the
> sides are hardware cloth (wire mesh), not solid. I don't know if the
> moths can get through the mesh but they might get in under the roof or
> some other unprotected place. Juncos (small birds) sometimes get in; I
> suspect they walk between the bottom of the door and the gravel path.
> The protected situation also attracts many spiders, which may help
> control the moths.
>
> Most advice on controlling cutworms in the home garden involves making
> little cardboard collars and putting them around the young plants. That
> is probably fine for somebody who is growing a dozen little plants --
> not a thousand.
>
> Jane McGary
> Portland, Oregon, USA
>
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