'June bugs' how big a problem are they?

For the first time since I have lived in San Diego County, I have a ‘June bug’ problem. I have noticed a couple of the bugs in the last two yrs (and I mean just a couple-no damage to speak of) but this year there are quite a few bugs (I think they are Phyllophaga hirtiventris) and they are eating foliage, flowers, and buds. Where they attack I am not able to use the bud/flower for hybridizing. I do remember the June Bug attacks that we used to get when I was growing up in Wisconsin and this is quite similar–but it is a slightly different bug species, darker brown, slightly wider and chunkier looking. What I remember from Wi. is the rose chafer, Macrodactylus subspinosus, with a few larger and darker bugs interspersed with them. Have these always been a problem with roses in California? Does anyone else have a good way of dealing with them that works, and since when did they become a problem in San Diego? I can see that these might become a problem with hybridizing but I do not remember any other mention of them.

First a sad story. Years ago, in California, I raised a seedling from ‘Mevr. Nathalie Nypels’ that grew well and bore very fragrant, cream-colored blooms. It began to weaken, and finally died. When I dug up the plant, I found that a nasty grub had chewed up through the tap root.

The grubs are just as damaging to roses (and other plants) as the foliage-eating adults.

Prof. Page (1857) offered this advice:
“The grub of the Beetle, commonly called the June-bug—a bronze green beetle, generally appearing in July instead of June—is very destructive to young roses, and often destroys large bushes. I have had many hundreds of seedling roses destroyed by them in one season. Where the roots are small and tender they will commence at the bottom of the tap toot and eat it entirely away up to the surface of the ground; and will often girdle the roots of larger bushes. There seems to be no remedy against them, but the destruction of the Beetles by saucers of molasses laid about their haunts, into which they will plunge and become entrapped. This grub is commonly known as the “fat worm” here, and is a sluggish, hideous insect, and when exhumed, crawls upon its back. They sometimes destroy whole beds of strawberry plants, and also whole acres of potatoes. It has been at times very destructive to the potato crop in Europe, and deserves our special attention.”

Here’s another report of success with molasses, mixed with water in an old mayonnaise jar.

And one more:
The Soil of the South 3(3): 464 (March 1853)
“Several years since, finding my apples all punctured by a worm which caused the fruit to fall early, I adopted a mode which I found recommended by some author, I think the late lamented Mr. Downing, with much success. I procured from an apothecary’s shop some fifty empty quinine bottles. In each I placed about four tablespoonfuls together of molasses, vinegar and water, and suspended them with a cotton string among my apple trees. The destruction of moths, wasps, Fig Eaters (commonly called June Bugs) &c. was immense. This I prosecuted from April to August. The only trouble was to renew the syrup after every rain. The succeeding year my apples were almost entirely exempt from attacks by the apple worm. I conclude from this experiment which I made for two successive years that I must have destroyed many thousand of the applemoth, who deposits her eggs in the flower as the young apple is forming. I found also that the cabbage worm, which riddles so many fine heads and is occasionally found ensconsed among the tender leaves when served on the dinner table, gave me very little trouble. I conjecture from the result stated, that many of the Cabbage moth had shared the fate of the great foe of the apple.” — Iverson L. Harris

On susceptibility to pests:

Amy Monahan of Spartanburg, South Carolina (Henry Kuska’s newsletter) wrote, “When Golden Showers was bending over from the weight of the Japanese Beetles ten feet away sat Mrs. B. R. Cant and Marie Pavie untouched. They remained untouched all season. Queen Elizabeth, Don Juan and Montezuma all had attacks. I don’t think my baby plant of Heritage did but then Heritage wasn’t blooming at the heaviest attack stage of the season. Golden Showers got hit every time she bloomed even when I wasn’t seeing JBs anywhere else: she would lure them out of hiding.”

Percy Wright (1978) wrote:
“No one seems to have made it a special aim to breed for resistance to the rose curculio, or snout-beetle, which devastates shrub roses in an enormous area of the Great Plains, in both the U.S. and Canada, and the reason for this appears to have been the lack of a realization that roses do exist which do not attract this pest, even when their period of bloom coincides exactly with the maximum abundance of the pest. The two species which I have observed to be immune to attack, or nearly so, are Rosa laxa Retzius and the as-yet-unnamed species which has the everyday appellation of Ross Rambler.”


The big green beetles, AKA June beetles, are generally known as fig beetles here: They coincide with the first crop of figs and since they are attracted to anything sweet, the molasses story makes real sense. They do go after roses but much prefer figs, which I do have. Might have to try this. An aside story–when my kids were small and right after we had seen the movie “Dumbo”, we had an attack of the fig beetles. One of the kids, equating the clumsy flying of fat little Dumbo on screen, yelled to me-“look, we have Dumbo Beetles” and Dumbo Beetles they have been ever since. Fat, dumb and knocking into whatever gets in their erratic flight paths. I have to explain whenever I see Dumbo beetles what I am talking about.
If molasses works on the Phyllophaga hirtiventris type of June bug, then the problem will be solved—they are only attacking selected varieties, eating blooms and foliage pretty fast. These have never been a problem in the 40 yrs I have been in the southwest. It seems like it would be a selective breeding project worth pursuing if it is a problem elsewhere.

It might be helpful to keep a list of rose varieties that seem resistant and of those that are severely infested.

The genus was formerly named Lachnosterna. Searching on the old name I learned that Tiphia inornata, a black Scoliid wasp, is parasitic on the grubs of Lachnosterna spp. There was an attempt to establish T. ornata in Puerto Rico where the Lachnosterna/Phyllophaga grubs were a serious problem in the sugarcane fields. I don’t know whether it was successful.

Seems like this time each year, we have a wave of the big brown nocturnal beetles eating the roses (and also some other stuff like fruit trees). This year they’ve been particularly bad. I’ll have to use this opportunity to see if there are any roses here that they seem to avoid. They definitely AREN’T avoiding my F1 davidii X fedtschenkoana!

I think ours are some species of Phyllophaga too.

It doesn’t help when trying to work with once-blooming species roses… but at least it’s always seemed like these beetles are only bad for a couple of weeks at most.

Better living through chemistry!

Imidacloprid is undoubtedly one of the most dangerous, destructive insecticides ever released to the general public. I don’t think that is hyperbole. Banned in Europe because of death of bees, which is rather well documented. Systemic, long-lasting broad-spectrum, sure to spread contamination through improper use and run-off into streams. Notice it is prohibited around NYC. I hope this is an old ad. My grandfather used to sell arsenate of lead before 1930. I have an empty crock in my office. Places that once had orchards are still dealing with the aftereffects. DDT is still a big problem in Kazahkstan, and many other places. All of west Africa has issues with obsolete pesticides that kill people. When will Bayer give it up?

Some of my roses and my Concord grape are currently under attack from the green-bronze beetles. I just bought some molasses to learn whether it will get rid of these pests. I’ll let you all know what happens.

The molasses was not a miracle cure. Maybe I should have started earlier in the season. I got so annoyed with the critters on my grape vine that I swatted them into the molasses. They stuck, but it rather defeats the purpose of setting a trap if I have to knock them into it.

I have been going around the garden with a plastic cup full of dish soap and water. I flick the Japanese beetles into this nice clean bath and it kills them quite thoroughly, but you have to be vigilant. Not sure whether this is cause and effect or coincidence, but they have tended to stay away from roses with feverfew growing next to them. I got a packet of feverfew seed a couple of years ago and it comes up everywhere now.