soil grub/larva, good or bad?

Asked February 9, 2018, 11:46 PM EST

I'm encountering a soil grub that is fairly dark gray, more or less. Head is darker than body. Length is approx. 3.5 cm. width almost 1 cm. It's body is quite soft at this stage and locomotion pods very rudimentary. It has 10-12 segments. The first three segments have two locomotion pods each, starting from behind the head. Segments 4 & 5 do not, but segments 6--9 each have what appear to be locomotion pods too as does the last segment. One of these I encountered was positioned in a fairly tight 'C' shape but others were straighter although still somewhat curved with the back more exposed than the underside. My question is whether this organism is harmful in any of it's stages to my lawn or garden. If so what would be control measures?

Multnomah County Oregon soils

8 Responses

Thank you for your questions. I can’t be of much help without a closeup photo and information about what plants grew in this area last year. I’ll help with more info. Thanks!

I will try to include photos. This grub was first noticed where strawberries were growing but it has been found in nondescript areas too.

I am unable to get my photos to transfer to this response. Is there another email address I could use so I can send the photos as attachments?

Carl Bankes

Glad to, Carl.

From your photos, it appears you have a cutworm larva. (I'm attaching the photos you emailed to me, in the event another expert has a different identification.) These will mature into a moth in August or so. In the meantime, they will eat their way through foliage in your garden. This Extension article has suggestions for controlling this pest. Since 'collars' can be effective in keeping them from reaching the foliage, I'm assuming these cultural and physical controls will be more appealing, to avoid using pesticides around vegetables and fruiting plants.

I hope this information is helpful. Good luck!

Thank you Kristena, I appreciate your efforts on this question. It has been quite helpful.

You're welcome, Carl. Happy gardening!

As i anticipated, Jean Natter identified ‘Noctua pronuba, aka winter cutworm. It has been eating all winter, whenever the night temps were 40F or above. It will be an adult moth in April or May.’ Control mechanisms still the same, just earlier.

Thanks for the additional information.