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Grubs in soil

Posted by squibt 7b (squibt@hotmail.com) on
Thu, Mar 25, 10 at 10:26

I have found quite a number of grubs in all of my flower gardens (just below the surface of the soil). None of the gardens have very many plants in them right now. Last year they all had different plants including hot peppers and a variety of flowers...can anyone identify them...

Photobucket


Follow-Up Postings:

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RE: Grubs in soil

Looks like a cutworm. These tend to reside just below the soil surface and emerge in evening or at night to feed on tender new plant growth. Not a nice critter! I squish 'em when I find them but you can take a more proactive approach. Sluggo Plus includes the biological control spinosad, which is effective against cutworms but there are other products that include this ingredient as well.

Here is a link that might be useful: cutworm fact sheet


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RE: Grubs in soil

I have found a bunch of these lately too. I will squish them from now on. I use a lot of Sluggo Plus already but still have found a ton of these worms.


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RE: Grubs in soil

Beetle grubs look similar, and some beetles are beneficial, but you can probably squish these grubs that are in your garden beds without depleting the area's population.


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RE: Grubs in soil

  • Posted by jean001 z8aPortland, OR (My Page) on
    Fri, Mar 26, 10 at 0:25

Those caterpillars are more than likely the greater yellow underwing, the technical name Noctua pronuba. (The adult is a moth.) They overwinter as caterpillars and come out to eat on warmish nights.

You can find them about 10PM or so if you go out with a flashlight. To find them, inspect the edges & undersides of the leaves.


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RE: Grubs in soil

Thanx for the replies...I remember last year some of my plants were really chewed up and I could not find out why. I will check them at night this year.


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RE: Grubs in soil

jean, very interesting; I have taken much notice of a local Nocuta moth and have several collected from my backyard--but these are Nocuta comes, the Lesser yellow underwing. I have never seen a Greater around here, although both kinds are documented in the PNW. The Lesser is smaller and has a small black arc on the hindwing, besides the bold black border common to both moths. It started showing up here suddenly in numbers around the year 2000. Both moths are recently introduced to the U.S. from Europe.

If you can find a moth without the black arc in PDX this summer, please post about it (would probably have to be captured because the black arc does not show during normal moth posture).

The image above does not look like a typical moth cutworm to me; by the time they are that large they should have some striping or black dots along the sides.

But moth cutworms do occur on and just under the soil surface.


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RE: Grubs in the soil

Forgot to put research links above; these show the larva
and comparison of adults:

http://www.goodbugs.prosser.wsu.edu/grapes.htm
http://commons.wikimedia.org/wiki/Noctua_comes


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RE: Grubs in soil

That doesn't look like a cutworm to me, either.

If you have a lot of those type of caterpillars, a good clean up of plant debris in late summer or fall can reduce the places they need to lay eggs and overwinter.


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RE: Grubs in soil

There are 650 species of cutworm or armyworm found in Washington state. I'd be pretty impressed if one of our forum members was that well-versed and knowledgeable about these creatures that they could ID them all and determine with certainty that the one illustrated in the above photo was or wasn't included in that very large grouping.


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RE: Grubs in soil

It is certainly not an underwing caterpillar. I've collected insects for decades and the above image just does not look like a moth caterpillar to me.

By any name, they will be just as squishy.


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RE: Grubs in soil

  • Posted by jean001 z8aPortland, OR (My Page) on
    Thu, Apr 1, 10 at 12:09

I5t was said "That doesn't look like a cutworm to me, either"

It was also said "It is certainly not an underwing caterpillar."

Well, sorry, but it is a Noctua moth. That's how they look just prior to pupation. Very fat & very squishy.

So if OP still has it, I hope it's in a container & is being observed daily. After pupation is complete, you'll be able to ID the adult moth which emerges.

Or if the original is long gone, do the same rearing thing with the next one you find.


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RE: Grubs in soil -

  • Posted by jean001 z8aPortland, OR (My Page) on
    Thu, Apr 1, 10 at 12:11

Another suggestion to OP -- Can you post a *much* larger version of the image? Doing so should help settle some questions folks have.


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RE: Grubs in soil

Fat and squishy, yes, but they wouldn't lose their distinctive coloration.

UofIdaho Info

It's just that I see cutworms occasionally in the yard and then many Noctua moths from mid-summer on, but I have not seen the posted image in the yard, soil or anywhere.

I hatched out some tortrix moths a few years ago from a calamondin plant-feeding larvae. I will try to capture some cutworm and see what it becomes.


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RE: Grubs in soil

Notice that the lep is on its dorsum. In that position, one can't visualize the lateral markings -- they're closer to the dorsum than to the ventral surface.


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RE: Grubs in soil

Hope this pic helps

Here is a link that might be useful: Bigger Pic


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RE: Grubs in soil

  • Posted by jean001 z8aPortland, OR (My Page) on
    Sat, Apr 3, 10 at 13:43

squibt,

Thanks for trying. But what we need is a large image of the critter itself.

Do you perchance still have the critter?

If so, rear it to an adult as I suggested above. If you don't have -- much more likely, right? -- then rear out the next one you find, then post a picture of the adult.


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RE: Grubs in soil

squibt kindly emailed me the original photo, here is the snippet of larva, original size and unretouched:

There is plenty of detail in this image to determine the order of insect this is a larva of.

(The original larva was supposedly squished and is unavailable for comment)


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RE: Grubs in soil

Just a follow up...this grub/caterpillar decimated a few of my flowers near the end of summer last year. They ate most of the leaves from my pepper plants too. They did not cut the stems around the bottom of the plants or cut off any other stems....just ate leaves. There was no mulch or other debris for them to hide in and after the plants were eaten they were pulled up. I found quite a few in the same general area along a walkway....squished them all. I really need to know how to deal with them before they emerge again this year and after the garden is established. Organically please. Squishing them is an option but please gimme some ideas...I cant find them all. Maybe chickens?

squibt


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RE: Grubs in soil

It was said "There is plenty of detail in this image to determine the order of insect this is a larva of."

Yes, indeed. It's a caterpillar.

The head is at the left, next come 3 pair of jointed legs, then 6 pair of prolegs.


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RE: Grubs in soil

Finally, a break in the case!!

I agree the head is on left and there are three pairs of thoracic segment true legs, but--

All noctuids have 4 pairs of mid-abdominal prolegs, except for the subfamily Plusiinae that have only two.

The highest number of proleg pairs in the order Lepidoptera is five.
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Partial identification key:
5'. 6 to 8 pairs of abdominal prolegs present
(Order Hymenoptera = Bees, wasps and sawflies)

5'. 2 to 5 pairs of abdominal prolegs present
Caterpillar (Order Lepidoptera = Butterflies and moths)

6. 2 pairs of abdominal prolegs
Looper (specifically, Geometrid caterpillars: Order Lepidoptera)

6'. 3-4 pairs of abdominal prolegs
False looper (specifically, Noctuid caterpillars Order Lepidoptera)

6". 5 pairs of abdominal prolegs
Caterpillar (remainder of Lepidoptera)
---------------------------------
Also, all lep cats have 10 abdominal segments, and I can only see 7, or possibly 8 (including the anal segment) in the image.
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Cutworms can also just chew leaves, it's just another form of cutting. The caterpillars that chew big holes in my rhubarb look like cutworms.


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RE: Grubs in soil

  • Posted by jean001 z8aPortland, OR (My Page) on
    Sun, Apr 4, 10 at 13:03

It was said "The highest number of proleg pairs in the order Lepidoptera is five. "

Yes, I goofed in my previous post.

Noctuid caterpillars (moths) have 5 pair of prolegs. Four pair are obvious on the abdomen with the 5th pair at the tip of the abdomen and often appearing as if fused.


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RE: Grubs in soil

At my request, once again squibt provided more images:


Definitely a noctuid moth caterpillar. The right number of segments and prolegs. One can just make out the "crochet" hooks on the true legs. It does lack the markings typical of Noctua, but I will investigate further.

Organic control methods:
- a stiff paper collar around plants to be protected
- remove lawn or weedy turf near vegetables
- diatomaceous earth
- molasses around plant
- wood ash around plant
- have a good bird habitat


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RE: Grubs in soil

Thanx again everyone....esp. Larry


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RE: Grubs in soil

What is the bottom line? should I be squishing them or not? I've found dozens of them so far this year....


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RE: Grubs in soil

  • Posted by jean001 z8aPortland, OR (My Page) on
    Thu, Apr 8, 10 at 18:14

Bottom lines are these:
1. It's a caterpillar, which eats leaves of your favorite plants throughout the winter (when it's warmish) and through the spring.
2. It will grow up to become a moth which will mate and lay eggs.
3. The eggs will hatch (fall) and more caterpillars will be eating leaves at your place.

So, your choice. Squish them, or drown in soapy water, or snip in half, or feed to the birds.
But if you are the non-violent type, let them live.


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RE: Grubs in soil

These particular moths are medium-sized brown ones that reveal a flash or orange on the hindwings when disturbed.

They do not tend to roost on flat walls like some moths, but hide out in dense foliage during the day. You can test for the presence of adults by directing a spray of water into a dense shrub such as juniper. They will fly off. If you find them in your garage trying to exit through a window, you can capture and kill them as adult moths, but odds are, they have already laid eggs.

Much thanks to jean for the postings; now I can tell the difference between the Noctua species and their larva.


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RE: Grubs in soil

Something has eaten some of my potted Clematis in my pot ghetto to bare stems and huecheras and bergenias in the garden are chewed worse than I've ever seen. I've been spreading Sluggo Plus since February and my daylilies and hostas look fine but I'm worried about the Clemmies.


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RE: Grubs in soil

  • Posted by jean001 z8aPortland, OR (My Page) on
    Sat, Apr 10, 10 at 0:55

buyorsell888,

Because the Sluggo isn;'t working, you need to look for the above mentioned caterpillars. Do so at night -- 10 pm or so -- with a flashlight. They're very busy these days.


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