Japanese beetle grubs

Hi,

I dug one of these up in my garden the other day. Boy was it gross! I didn't know what it was until after the fact, and tossed it over my shoulder into some empty dirt. Should I have killed it? Are these really bad? Please let me know.

Thanks!

I kill all grubs that I find. He probably burrowed back into the dirt.

A few are no big deal, and grubs serve a purpose in the garden like anything else. But a big JB infestation is awful. If you're getting a whole lot of grubs, consider beneficial nematodes (www.groworganic.com) or milky spore.

I don't think I have a big population, so if they're beneficial in small numbers I'll leave them be. I only saw the one, and I do recall getting the adult beetles around the same time as the June bugs (in June, go figure...).

Thanks! :)

These grubs mature into Japanese Beetles that eat roses, etc. Also, they attract moles who feed on them. If you have one, you usually have the other. My advice is to get rid of them before they take over your yard, which they will .

P.S. Grubs feed on grass roots. Do you have brown patches in your yard? If not, you will.

Japanese Beetle grubs are never beneficial in any number whether it be only one or a hundred. Could very well be that you unearthed a June Bug grub given the time of year you are posting. Many grubs are totally harmless while others are not only harmless but also beneficial but as mentioned, there are a few that are extremely destructive. You are wise to leave them be since you aren't sure what type of grub you have as opposed to running out and loading up your property with chemicals which may or may not be effective. Always best to get a grub properly identified before any action is taken even if you have to place it in a cup and walk it in to a landscape service to ask what you've got. Most people are pretty good natured when you walk in looking helpless with a grub in a cup. Have you ever heard of the "Butterfly Effect"? Truly an awesome philosophy.

Most of my grubs are exposed in the grass when I'm digging a new bed. They are June bugs or Japanese beetles. I will continue to kill them.

Well billyporter, kill on! When I garden and create new beds which exposes grubs, I leave them exposed and sure enough a crow will come along and gobble up those juicy morsels. Everyone has their threshhold. I know I certainly don't want feral cats anywhere on my property and grubs are considerably less attractive.

Many of the cotinus spp. are integral parts of our North American ecosystems though and when we tinker with one part of the equation... there is a ripple effect. There are many species of North American flora that depend on the existence of grubs for survival. Insects (including grubs) are an extremely important food source for many vertebrate animals (fish, birds, amphibians, lizards, snakes, and mammals, as well as other predatory insects). Just something to consider.

Except for a very occasional mole and birds, we just don't have anything that preys on them.

Well now you all have made me curious. I'll try to dig another up (if I find one) and bring it to my nearest nursery. It looked just like the photo of the japanese beetle, but then I'm no expert. Truthfully, I looked at it on the end of my trowel and said "EWWW" and flung it away very quickly, so my identification process was not scientific to say the least! :)

We do have brown patches all over the lawn, but only since the arrival of a new female lab puppy whom is using it as her potty area. We're experimenting on what to do about that, but that's a story for another forum.

Thanks, Christina

Hee about the lab puppy, but brown patches might be better than holes or "travel paths" that can also be a side effect of having a dog in your yard. At least the brown patches could be temporary. An industriously dug hole might be an entirely different battle.

As for the grubs, take it from someone who has to dig out her lawn insect reference and turn it to the grub section whenever I get a grub in for identification, a quick look isn't usually enough to ID these guys. The main way to identify them is by what's known as a "rasta pattern" which is a pattern of setae (short, stiff hairs) on the underside of their little grub butts. It is pretty distinctive as long as you've got the drawings to compare it to, but you usually need a dissecting scope or strong magnification of some sort to see the patterns. My reference has about a dozen or so similar type grubs that are identified by the "rasta pattern", but otherwise look very, very similar.

And unfortnately size may not be of help, because even though some June bugs will have bigger grubs later in their life cycle, the earlier instars may be of similar size to the Japanese beetles. There are also some smaller sized beetles in the "Scarab" category - especially a goldish one with black splotches who's name escapes me now but is quite common - that are fairly harmless.

I like to keep my scarab beetles around - my cats love playing with them, and I have a small bat population that I like to have nocturnal insects around for them to eat. I also apparently have shrews somewhere - I know that only because I sadly found one drowned in my fish pond. I now make sure to have a pile of rocks that reaches the surface and side of the pond, so that any critters that fall in can get back out. (Well, as long as no visiting puppies knock it down: roaming lab puppies especially - coincidentally - seem to enjoy "playing" in my fish pond. Hubby finds this rather humorous - me, not so much.) And I'm pretty sure that grubs sound like something that would be on the shrew menu.

Japanese Beetles are a big problem here eating Hibiscus blooms before they open, defoliating completely some of my shrubs and hedges.
When I dig in the yard and find any type of grub, I have taken to squishing them and tossing them onto the driveway where birds can find them.
I just squish them with my fingers, don't bother me at all considering the problem they have created in June and early July for me.
I also pick off the adult Beetles from my plants and throw them into a bucket of Murphey's Oil soap and water to drown. It is a war here.
There are some black ground beetles who feed on dog feces in the yard. I pick it up a few times a week, but they help to decompose it between times. I leave them be unless or course they are in the feces pile. YUK!
There are always plenty of bugs to go around and I don't think I will make a big dent on their populations in general, just in my garden.
I always kill them as I am usually planting something in the spot where they are and don't wish to have the roots of my newly bought or nurtured plant eaten.
Go ahead, squish them and toss them to the birds.
What good are June bugs? Are they something special? What do they eat, or is it that they are just cuter?

hope this help http://davesgarden.com/forums/t/269462/

Hey Night_Bloom, I thought I was the only one who did this, "I now make sure to have a pile of rocks that reaches the surface and side of the pond, so that any critters that fall in can get back out".

I find these two publications to be invaluable resources-
-Diseases of Trees and Shrubs published by Cornell University Press is authored by Sinclair, Johnson and Lyons
-Insects Which Feed on Trees and Shrubs published by Cornell University Press is authored by Johnson and Lyons.
Expensive, but worth their weight in gold. Grub identification is very tricky as mentioned by Night_Bloom.

I use pheromone traps. They are definitely species specific and I do believe they work. You must empty the traps regularly. Some weeks you will be out there emptying them daily.

Wow, who knew that there was so much to the 'ole grub! Thanks for all the information. I still haven't found another, but then I haven't had a bunch of time to dig as of late.

Night Bloom, you mentioned the 'cow trail' path around the lawn so you'll get a kick out of this. We had a concrete path poured in a free form design completely around the perimeter just for our dog. She didn't like her toes getting wet, so I guess that makes us one of those crazy people! It has the fringe benefit however, of being able to walk to the back of the garden in my slippers in the early morning. I like to check out the flowers as a nice way to start my day while I'm sipping coffee.

Thanks everyone!

I heard the pheromone traps work best in the neighbors yard since they attract the
insect in order to trap it. Both my neighbor and myself quit using them because they seemed to bring more beetle (Japanese) into the area than we had in the first place.
Even though it trapped them and they were disposed of, it did not make much sense to attract them in the first place.
You may have a different experience in your areas, but mine is definitely better off without them. We would end up with sacks full to over flowing with the little pests. Now I pick as many off as I can inthe early morning as they have wet wings and do not fly very well to escape. I place them in the bucket of Murphey's soap diluted with water so they do not swim out of it.

The pheromone traps are not a quick fix but they do kill the adults that are able to reproduce and although it is a lot of work, you are systematically and methodically reducing the number of adults capable of producing offspring. Frustrating, yes. But the traps do significantly reduce their numbers and if you have a few neighbors who hop on board, your can substantially decrease their population numbers in the surrounding area. Imagine the toll we could take on their population numbers if many people were using the traps.

Equilibrium's reference book suggestions are good ones. I have both of those myself at my lab, and I use the insect one all the time. If those are too expensive, another helpful reference for the insect part that isn't quite as extensive, but is also extremely helpful (and not so expensive) is "Garden Insects of North America" by Whitney Cranshaw. Lots and lots of pictures (in the 100's at least) with over 600 pages of information and photos. The price seems to range from $25 to $30 something dollars depending on where you get it (mine has a price of $29.95 on the back). It is helpfully grouped into the type of damage - though it might take a few tries to find your critter if the damage is more "general". I use it all the time as well.

Oh! Great suggestion!
I don't have "Garden Insects of North America" by Whitney Cranshaw. I think I need that. Particularly if the photographs are good.

Equilibrium: the pictures are very good. They are not large - many pages have 8 or so pictures on them - but they are of clear quality and there isn't a alot of extraneous stuff in the pictures (i.e. they are nice close ups). It also often includes more than one life stage of many of the pests, with emphasis on the larvae or nymphs and the adults (not so much the eggs or pupae).

Some of the images in the book not taken by the author came with permission from a site called bugwood and its offshoots (the main site I will give you here has 4 other sister sites). All of the pictures in the site are available for use in educational endeavors if credit is given to the photographer. I use this site often in my work when I'm looking for pictures to confirm an identification, especially for forestry related insects.

Here is the site if you want to check it out... http://www.bugwood.org/

Thanks for mentioning that the images in that publication were small. I have enough problems with small print as it is and keep a magnifying glass here by the computer to be able to look at images on the screen sometimes. I also keep a magnifying glass in my pocket when I go out. I just don't see well. Is that Cranshaw publication a good value for the text?

The photos at Bugwood are good. That's a real nice online tool.

You seem to like bugs likes me. By any chance are you comfortable with odonata identification? I've got a few that I never could id last year. I'm relatively sure a few are juvenile dragonflies and one was a damselfly. Needless to say, odonata identification can be challenging and I'm sure you know why. I gave up after a few weeks of trying last year when even the ones that had very different characteristics started looking alike. Frustrating, very frustrating for me at least.

Night_Bloom, perhaps you are the very person who could answer a question for me. I have a very small pre-formed pond, and until this year, had goldfish in it as well as plants. This year I do not plan to put in fish. So, I bought "Mosquito Dunks" to kill mosquito nymphs in the water. I did find out that Bacillus Thuriengi is harmful to butterfly larva, but I do not think that will matter for the pond. My concern is will bt cause any harm to amphibians or to the birds who like to drink from the pond? I look forward to the frogs and the ribbon snakes and garter snakes in the yard. Anyone who could tell me, I would appreciate it. I will not use it if it is harmful to amphibians or birds. Thank you, BAM

I can answer that question. Although there are some strains of Bt that are indeed harmful to butterfly larva, the strain of Bt used in mosquito dunks is target specific to mosquitoes. It is actually BTI. BTI = Bacillus thuringiensis ssp. israaelenses. It is actually the toxins that are produced by the bacterium that do in some types of mosquito larva (mostly Aedes species which are our bane). This toxin is termed delta-endotoxin. It will also work quite effectively against fungus gnat larva. No toxicity to fish, birds, non-target invertebrates, pets, wildlife, people, or plants. How about that for an ideal Biological Control! So bambamdryad, use your mosquito dunks with wreckless abandon because my dogs actually go out and drink treated water and suffer no ill effects what so ever. I treat every water feature I have here to include bird baths and water trays for carnivorous plants. I love those mosquito dunks. I should buy stock in that company.

I find integrated pest management to be very exciting. For anyone interested. check this link,
http://www.nal.usda.gov/bic/BTTOX/bttoxin.htm

Here's a little more that will make your heart flip with joy regarding the BTI and what it does to mosquito larva. This man Jim Deacon has such a way with words-

"Once it has been solubilised in the insect gut, the protoxin is cleaved by a gut protease to produce an active toxin of about 60kD. This toxin is termed delta-endotoxin. It binds to the midgut epithelial cells, creating pores in the cell membranes and leading to equilibration of ions. As a result, the gut is rapidly immobilised, the epithelial cells lyse, the larva stops feeding, and the gut pH is lowered by equilibration with the blood pH. This lower pH enables the bacterial spores to germinate, and the bacterium can then invade the host, causing a lethal septicaemia."

Jim Deacon
Institute of Cell and Molecular Biology
The University of Edinburgh

Oops, forgot to mention that the BTI would not be harmful to any fish in your preform or any critters that visit other than mosquitoes and gnats.

Equilibrium - The images in the Cranshaw publication range from about 1 1/2 inches square for the small ones to 1 1/2 by 2 1/2 thereabouts for the medium photos to quite a few in the 2 1/2 by 3 1/2 etc. area. Though on the realtively small side - since there are usually about 6-10 images per page - they are pretty clear pictures, so that is a plus. The book itself is a larger field guide - about 7 1/2 inches by 11 inches, and at about 650 + pages, it aint light, so it is not a pocket guide by any means.

The text is also helpful. As I mentioned, it is organized in sections of damage, so you can go to the "leaf chewers" section or the "sap suckers" section without having to decide if you have a beetle or bug or a larvae/nymph or adult first. The critters are arranged by those categories (beetle, bug, fly, etc.) after that main "damage type" section, but that still makes it easierthan looking through all the beetles to find theone that is feeding on your fruit - that's another section "flower, fruit, and seed feeders". You might also enjoy the rather nice almost 30 pages of beneficial critters that includes predators, parasites, pathogens, and pollinators.


bambamdryad - Equilibrium covered the informationon the mosquite dunks very well - I have no need to elaborate except to say that I use them in my small fish pond all the time with no problem, and I too often have a visiting frog or two. None so far this season, but I'm hoping I get one like I usually do each year.

Equilibrium, thank you so much for your prompt, informative response!
I kept wondering what the answer would be, and could hardly wait to check this morning! Thank you so much. It is wonderful to find such well informed people in these forums that can answer worrisome questions for the rest of us! LOL! Ty also, Night_Bloom. I am sure you would have answered if Equilibrium had not taken the first opportunity. I am grateful, and it will greatly ease my mind. Too often products are sold without enough information regarding any harmful side effects. I am a happy dunker this morning! BAM

The Johnson and Lyons publications are anything but field guides... unless one has a nice backpack. I'll order the Cranshaw publication. One can never have enough nice photos of bugs!

Say, light reading but have you ever read "The Forgotten Pollinators" by Buchmann? You might like that.

Hey BAM, glad you're a happy dunker.

Equilibrium - too true about the Johnson and Lyons publications - heh. I sometimes lug them home with me at night if I have an identification bugging me that I just have to research at home, and I usually use an over the sholder tote bag to lug them around.

I don't know the Buchmann book, but I'll definitely need to take a look. I'm always curious about the other non-bee and butterfly critters - like the flies, beetles, ants, etc. - that visit flowers, and the role they play.

You know something, you might be just the tyoe of person to enjoy reading "Noah's Garden" by Sara Stein. She has another favorite of mine out there titled "My Weeds". I think you would be able to appreciate both of those books as well as her writing style. She will be missed. She died either last year or the year before. She was a great orator too.

Another book I didn't see listed is
The encyclopedia of natural insect and disease control
by Roger B. Yepsen , jr
Rondale books 1984
color pictures are all in one section - Probably doesn't matter , it's an old book and out of date .
It does have a section on when the bugs hatch or whatever they call it .
Now I have to go to book section and post book review .
Another book is Insects of north america by George C. McGavin 1993
long meadow press -- better pictures but Japanese bettle isn't in it

This message was edited May 11, 2006 2:21 PM

Yesterday was a great day here. Lovely and sunny, although very windy all day. Spent the day digging, of course. But, when going back to empty a bucket of weeds, I saw a very nice ribbon snake coming out of the rocks at the edge of the pond. Having the answer to the mosquito dunks, made me happy to see it, not worried. Also, the first hummingbird showed up yesterday. Happy day. No frogs here yet, but I hope soon. Very few here, it seems, compared to other areas I have lived. Thanks again. BAM

A few thoughts on grubs and Japanese Beetles...

Every landscaper and garden center I've consulted recommends against Japanese Beetle traps because the pheromones are so powerful and the Japanese Beetles will travel so far to reach them, you end up attracting more than you catch. Here's one reputable source that takes this position: http://www.uky.edu/Ag/Entomology/entfacts/trees/ef409.htm

As for picking or knocking them off the plants, that can be a bit challenging from a wheelchair but I find this method to be effective for the plants that are just beyond my reach. I place a foil lsagna pan with an inch or so of soapy water in it next to the plant. I use one garden tool to gently bend the plant over the pan and another tool to whack on the first tool. It sets off just enough of a vibration to send those brats into freefall. I get a perverse thrill watching those little black legs franticly and futilely trying to escape.

As for grubs, while I respect Equilibrium's ecosensitive approach, and I, too, practice IPM and lean heavily toward organic approaches (especially since I have a koi pond), I'm not ashamed to admit that as far as I'm concerned, the only good grub is a dead grub. I kill every one I come across, and get vicarious pleasure from the thought that I may have just eradicated an entire family line of those durned beetles. Since our property borders 40 acres of wetlands and marsh, a 55 acre tract of woods beyond that, and a 10 acre horse next to that, I doubt that the relatively minuscule number of grubs I kill each day is going to even be noticed in this ecosystem. I also doubt it is going to help much, except possibly to help allay my anticipation regarding what I'm going to be facing in a few weeks when they hit with a vengeance.

JB's are a major headache here in New England and if your neighbor has grubs, your garden has beetles. I use milky spore regularly and between that and the smack and drown approach, my beetle population and the damage they wreak has noticeably decreased in the past couple of years.

Regardless, they are a problem that requires vigilance. My entire yard is virtually all garden - a half acre's worth minus the house and patio - so JB's can be a real headache and we try hard to stay ahead of them. We went away for a weekend last year during the height of JB season and I came back to find that they had feasted on every one of my hollyhocks. There was nothing to be done except to cut them to the ground.

Hell hath no fury like a munched out hollyhock grower.

One more note: I designed my koi pond to specifically be damsel and dragonfly friendly by creating a boggy area inaccessible to the fish where they can breed and the larvae can grow. I have been rewarded with a generous population of these beautiful creatures.

When I have been unable to identify one or have had other questions, I have gotten a lot of help from the International Odonata Research Institute. Their web address is http://www.afn.org/%7Eiori/. They have extensive resources for identifying them and they also host chats and forums such as this for getting answers to questions and problems.

What works for me may not work for others. I'm still going to continue using the pheromone traps. From the University of Kentucky site shared above I found this which parallels what had been shared with me,

One must make a conscientious decision to empty out those traps daily and sometimes more than once for several weeks straight. If one is not prepared to commit to doing so, then I would agree they are not in the best interests of the person using them or their neighbors. If one is diligent and if one has neighbors who are also using the traps and diligently emptying them, I believe they are beyond effective. No, one trap won't cut it and one would end up with JBs out the ying yang but several traps or several property owners with a trap each collectively working together can make a difference. Defoliation is going to occur, regardless of whether it is in the area in which they were happily chomping away or on their way to their death. These beetles do migrate although based on what I have read, they only migrate from about a mile. Although it is true the pheremone traps will lure them to the location of the trap, please know that the beetles were in one's immediate vicinity anyway. Very soon each female JB will lay around 50 eggs in nice grassy pastures and lawns. Two weeks after she has laid her eggs, they will hatch and become the grubs that we all love to hate. Bottom line for me is that the next generation will be able to emerge and repeat the cycle. In my opinion, every adult female one traps and destroys is one less JB capable of reproducing itself 50x which over the long haul will equate to less destruction of plants.

I believe my traps have substantially reduced the number of adults capable of reproducing in my immediate vicinity and I have noticed my Oaks are looking much greener these days because the JB party is over. No more smorgasbord! I did stop watering my lawn which may have helped too.

Loved those comments. I myself hate JBs and will waste them with wild abandon. The problem is people who come to me with firefly grubs and want to nuke them because they are convinced they are evil and then everyone wants to know where all the fireflies have gone??? Know thy grub.

Great photos of JB grubs here- http://sunny.crk.umn.edu/courses/gfts/3072/Mod16_Common_Insect_Pests_of_%20Home_Lawns_outline.ppt

Hey Seaside... did you know there is a brand new forum here called Gardening For Wildlife?

http://davesgarden.com/forums/f/backyardhabitats/all/

I think it might be right up your alley. There are an increasing number of people who are interested in Odonata. How you designed your koi pond is way cool, "I designed my koi pond to specifically be damsel and dragonfly friendly by creating a boggy area inaccessible to the fish where they can breed and the larvae can grow. I have been rewarded with a generous population of these beautiful creatures." I hope you share your design with others who would be very interested in what you did.

I've heard very good things from several people about the effectiveness of beneficial nematodes on the JB larvae, even shortly before adult emergence.

When I first bought my house some 5 years ago, JB grubs all but destroyed the lawn. I used milky spore. Being impatient, I applied beneficial nematodes to the section in front of the house (that was all I could afford. that stuff is not cheap). Then I applied a chemical grub treatment to the entire lawn except for the area treated with nematodes. Oh, and I didn't apply all of these things at the same time.

The lawn survived. But the area in front of the house (nematodes) is far, far thicker, lusher, healthier than any other section of the yard by far! One year after treatment that section of lawn was getting compliments from people passing by on the sidewalk who could see the miraculous turn around (it had been almost bare dirt at one time).

If I had a grub problem again, I'd go with the nematodes if possible.

I always say, "Better living through chemistry", lol

Best;
bluelytes