Algae control is as easy as A-B-C 1,2,3 - R Calcium bentonite [Koi Clay] works very well at killing and suppressing algae growth, but first: 1. If your pond has a gravel bottom you may need to debulk the nitrogen and phosphate load first by pressure washing string off of the side wall rocks and and the using lower pressure with more volume to wash the muck down to the lowest level where you can sump pump it out to the benefit of your gardens and trees. I did this in early June [after a few year's hiatus] and my ponds water has remained nearly crystal clear since, just from that. 2. After your water has stabilized, ~ 24-72 hours, depending upon your filtration method, you may reintroduce your Koi, and resume normal feeding cycle, using extra caution to avoid overfeeds, prevent over wash heavy rains, which can raise nitrogen and phosphate levels. 3. Then you must decide you methods for long term string algae control. control that and you won't have any of the other stuff in significant amounts to worry about. A. Netting, removes string and removes its incorporated nitrogen and phosphate out of the ponds biochemistry. If you wait until you have a lot it is hard on your back and the results are as a whole unsatisfactory, but it is easier to debulk living string or blanket weed while it is a live and buoyant, than after it has sunk to bottom and is doing a good job of starving your Koi of critical oxygen. So, net what you can and kill the rest, while upping your preventative methods. B. Chemical algaecides [non copper containing, so that snails and crustaceans remain unaffected], not only kill visible string algae, but its spores and initial growth Sodium carbonate peroxyhydrate essentially harmless to plants, fish, and other aquatic fauna is spread over the surface wherever filamentous [string, blanket] algae are found and sinks down onto their strands for a very potent contact algaecide, but as it dissolves does and equally good job on planktonic free floating single-celled algae which cloud and color water green, ultimately turning your pond's water into thick pea green soup, if you nitrogen and phosphate levels are high enough. PAN [Poly(oxyethylene) (dimethylimino) ethylene (dimethylimino) ethylene dichloride], the active ingredient in Algaefix, though it must be used with some caution not to overdose or you may lose Koi. Some web essayists have made much of the LD50, of Algaefix, and it is important to remember this when using the product, but the LD50 of many therapeutic drugs necessary for survival with some diseases is not much different than Algaefix for your Koi. If you must use, use wisely! C. Calcium Bentonite marketed as Koi Clay at /substantial markup/ is mined as diatomaceous earth and proves toxic to both filamentous and planktonic algae and also serves as a flocculant binding small debris-particles which then sink to the bottom or become processed by the specific biofilter utilized. Calcium and other trace elements found in powdered calcium bentonite improve Koi color and plant health, such that the ponds circulation and natural nitrogen cycle provide everything your fish, small creatures like frogs and snails, water lilies, and other aquatic plants require to grow. Making the addition of plant 'fertilizer' unnecessary and counterproductive visa vie the algae issue Remove dead aquatic material and debris before it breaks down and enters your pond's Nitrogen cycle, or you will have plenty of string algae to remove later, no matter what you do. Happy Ponding!

I was going to suggest nematodes, but I see you've already found that. That's the only solution I know of. I think these are Japanese beetles. I have LOTS of them; any time I dig new sod they're everywhere and I dispose of most of them as i find them into a bucket of water. The good news is that despite all the grubs, I've never actually seen a Japanese beetle, and I do a lot of gardening (flowers and vegetables), so I don't consider them a problem. If you don't have a problem with the beetles, my advice would be just ignore them and dispose of them as you come across them. Bugs really only become a problem if they bite you or start eating your plants. At least that's what I've come to believe...

Forgetting all those things that don't work and going to the vet and getting the flea bombs they carry and use the flea treats you feed to the dogs is the only thing that worked for me after the borax and salt on the carpets and vacuuming constantly. Also, spray the yard where the pests hang out, too. I am flea free now and I had a lot of them.

Look up "May beetle" AKA "June beetle" and see it it matches the brown one. (A lot of things go by that name.) They can be really common for periods and there is no reason to get rid of them if they aren't doing visible damage to your yard. Don't get rid of an animal just because it is THERE. Only get rid of it if it's a problem. Was "a couple inches or less" a typo?