What is this beetle?

Question: Hello, I put an insect net over my brassica bed to keep cabbage worm moths out, and ended up with lots of these inside the net. They may have wintered over in the leaves I covered the soil with. They are about an inch long. Thank you!

responder: An Ask Extension Expert Replied June 07, 2023, 11:03 AM EDT
response: Frances: I am sorry, but I cannot ID this insect. Is it possible could you or someone you know take a close-up picture of this insect?  Rich

responder: The Question Asker Replied June 07, 2023, 11:25 AM EDT
response: Thanks for trying. I will attempt to get a better photo. The problem is that they move fast. Stay tuned.FranSent from my iPhone On Jun 7, 2023, at 8:04 AM, Ask Extension <<personal data hidden>> wrote:﻿

responder: An Ask Extension Expert Replied June 07, 2023, 6:06 PM EDT
response: Wish you success.

responder: The Question Asker Replied June 07, 2023, 10:35 PM EDT
response: Hopefully these will help. Thanks so much!FranSent from my iPhone On Jun 7, 2023, at 3:06 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: An Ask Extension Expert Replied June 14, 2023, 10:44 AM EDT
response: Frances: From what I can see you likely have what we call a 'Leaf Beetle from the family Chrysomelidae. I say this due to where you found the beetle. If you get a chance, could you look at the plants to see if there is any damage to them. Let me know what you find. Rich

responder: The Question Asker Replied June 17, 2023, 1:50 AM EDT
response: Hi, Rich - I don’t see any leaf damage. I don’t see any more beetles, either. I really think they are something that overwintered in the soil-or in all the leaves I mulched the trough with. When I planted it in the spring, I put netting up pretty quickly, so I think these were mainly trapped inside, although there were some on the outside of the netting as well. Oh, well, another one of natures, great mysteries! Leaf beetle sounds good to me. I’ll keep observing the area and let you know if I see anything else happening there. My biggest issue this year is actually s symphylans! . I saw them last year in one bed, and now they seem to have spread to several others. I think I’ve read every single article that’s ever been written about them. I am an organic gardener with raised beds. I did try flooding, and then compressing the soil and that seemed to work on one of my lower beds. I planted potatoes there, so we will see what happens. Looks good so far. I hear contradictory things about whether symphylans go after potatoes or not. Meanwhile, my leeks, onions,  lettuce all seem to be standing up to the symphylan invasion.  I also created some kind of sandy areas for planting some things and so far those things are doing OK. I’ve also hand tilled and also hand-picked a bunch of them. Although I know that’s kind of futile, I can’t stop myself. I have limited space so I’ve been bringing in metal troughs and planting them, keeping them free from the symphylan in case I have to abandon those other beds. I would very much like to be in contact with other organic gardeners that are trying to coexist with this pest, if you know of any, will you please send them my way.?Thank you so much,FranSent from my iPhone On Jun 14, 2023, at 7:45 AM, Ask Extension <<personal data hidden>> wrote:﻿

responder: An Ask Extension Expert Replied June 19, 2023, 5:00 PM EDT
response: Fran: I have listed my information about this ‘pest’. Many of these you have tried but some others may be of some help. Your use of metal troughs is a good idea. Garden symphylans are difficult to control in the home garden. The following practices have shown some value but are not dependable for consistent or effective control: Cultivate deep and thorough with a rotating cultivator between crops to destroy earthworm tunnels, crevices, etc., as well as to kill the symphylans and any eggs that are present. Cultivation may also drive the symphylans deeper into the soil and decrease feeding on plants. Firm packing of soil over newly planted seeds fills crevices and helps to keep symphylans out since they prefer loose, noncompacted soil. Symphylan populations can readily increase to high numbers in soils with high organic matter and with good moisture-holding capacity. Using sandy soils for the garden may reduce symphylan damage. Symphylans may damage sprouting seeds, seedlings before or after emergence, or older plants. They feed primarily on root hairs and rootlets. Feeding may stunt transplants as new roots grow out of the transplant plug.The economic significance of symphylan feeding decreases as plants get larger and older. However, their pitting of roots may provide entry for pathogens, regardless of plant age.Symphylan damage occurs in well-drained soils with high content of organic matter, and especially in farms that fertilize with manure. Symphylans do not thrive in compacted or sandy soils.Numerous organisms prey on symphylans, including predatory mites, predaceous ground beetles, true centipedes, and various fungi, but little is known about their effect on symphylan abundance. Consider installing and maintaining insectary plants to attract natural enemies of garden symphylans.Reduce the amount of non-decomposed plant material and manure that is applied to the soil.Wait to seed or transplant until the cover crop, soil-incorporated weeds, and manure have completely broken down.Pack down the soil surface after planting to reduce crop injury.Plant a higher seed population in problem areas to help compensate for damage.Here are two articles from the Pacific Northwest Insect Management Handbook that provide more details about symphylans:Vegetable crop pests - Garden symphylanBiology and Control of the Garden Symphylan