Irobins
Contact the MD Department of Agriculture (after all it's you tax dollars at work-utilize them if you can). They should be able to direct you to the Insectary for the area They may also may recommend an APHIS facility (federal) in your area.
If they have them or can obtain them for you, the price is usually pretty low to nonexistant (here in Colorado there is no fee for biocontrol insects from the Insectary). Even if they don't have them they may recommend suppliers or other agencies that can.

Good idea; I will check first with the University of Maryland extension service. They have a web page specifically for submission of questions from home gardeners. Since this question-and-answer program is "made possible by a grant from the Northeast Regional Integrated Pest Management Grants Program, which is funded by the United States Department of Agriculture", one hopes that they will have good information on IPM.

Here is a link that might be useful: University of Maryland gardening questions

try this too:
http://www.mdipm.umd.edu/IPM/IPMLinks.htm
Good luck!

Ooo, lrobins, let me know what you find out! (We live next door to a no-till field planted alternately in soybeans and corn, soybeans this year...)

I actually tried to buy them 3 years ago when I was postdocing at the U of MD and they were running about $10/ wasp. We decided not to pursue the research for that reason.

I haven't found anything yet, but I am shocked to hear that someone was selling them for $10 each. How can an insect that is supposedly already common and well-established in the eastern US command such a high market price? Maybe the reports that it is common are untrue; or maybe this was a severe case of "beneficial insect price-gouging". This makes me more curious. I will report if I learn anything.

Here are some answers I received from Prof. Daniel Potter of University of Kentucky about Tiphia vernalis:

1. "I know of no commercial source for bulk purchase of Tiphia vernalis, although a few years ago there was [someone catching and selling them]. There is no research that would suggest buying a few hundred and letting them go on a property would have any benefit, however. Doubtless they are already there, and working subtly behind the scenes, taking a modest toll on the JB grub population."

2. To increase the number of Tiphia vernalis near you, and thus increase their "toll on the JB grub population", Prof. Potter suggests that you should PLANT PEONIES. "We also have seen [Tiphia vernalis] abundant at flowering peonies, feeding on the nectar, and even showed that parasitism rates on grubs in turf adjacent to peonies was higher than away from such flowers. So planting peonies in a home landscape may pay some dividends, although perhaps not enough to notice a reduction in JB densities."

3. The attraction of Tiphia vernalis to peonies is very specific: "We screened dozens of other kinds of spring-blooming flowers and most of them did not attract appreciable numbers of Tiphia." The Tiphia are attracted to "honeydew" produced by aphids and scale insects (that live on foliage of many types of plants), but not to flowers other than peonies.

4. To conserve (avoid killing off) the Tiphia, also follow this advice: "Avoid treating lawns with 'season-long' grub treatments, especially imidacloprid (Merit or Bayer Season-long Grub Control) in May, as that is when T. vernalis is most active. If preventive grub treatments are needed wait until June or July, which conserves the beneficial wasps." (Of course, you're doing the right thing for the wasps if you've "gone organic" and don't use any chemical pesticides.)

5. Prof. Potter also tested milky spore disease and found it to be of NO use: "milky disease spore powder (not effective in our multi-year trials; despite manufacturers' claims, there are no data supporting any benefit from its use in suburban lawns & landscapes)."

6. Prof. Potter also doesn't recommend the pheromone traps, writing "counter-productive, attracting many more beetles than they catch". Actually, I am disputing this point with him: my argument is that by attracting the beetles to one area (within a certain radius), the trap must be drawing them away from other areas, so the effect of the trap (beneficial vs. harmful) depends on where you place it in relation to the plants that are to be protected.

Here are more discouraging comments from Prof. Potter about the JB pheromone traps:

>> In our trials we tested JB traps on individual landscapes and on golf courses where the traps were placed 10 or 30 feet upwind or downwind of preferred host plants (those were the instructions on the boxes of various trap brands we purchased in garden stores). Also we tested lines or traps, triangular arangements, etc., always within a given yard. Our intent was to simulate what most homeowners would do. Invariably the test plants received MUCH more damage than if no traps were present. >> No one has scientifically evaluated the scenarios you propose, so it pays to be open-minded and experiment. I am skeptical that in an open system where JB is established, it will be possible to "trap out" enough beetles to make a noticeable difference. For example, they ran 5000 traps at the Louisville Airport for a number of years to try to reduce hitchhiking beetles getting on aircraft (to the West Coast) but finally gave up because they saw no measurable impact. Part of the problem may be that the beetles can fly long distances, so that if you set up traps in a limited area (even a few square miles) many more beetles just fly in from the surrounding area. Perhaps a really massive trapping program, that would extend beyond the flight range of an individual beetle, would make a difference. Maybe hundreds of thousands of traps, over hundreds of square miles, repeated year after year? Obviously, some organization would have to provide funding for such a massive JB control effort, and maybe it isn't a high priority because of need for control of other destructive insects and invasive species.

Here is the actual abstract of the article on the beneficial effect of Peony flowers (Peonia lactiflora) on parasitism of Japanese beetles by the Tiphia vernalis wasp.

Potential for Sugar Sprays and Flowering Plants to Increase Parasitism of White Grubs (Coleoptera: Scarabaeidae) by Tiphiid Wasps (Hymenoptera: Tiphiidae)
Environmental Entomology June 2004, vol. 33, no. 3, pp. 619-626(8)
Rogers M.E.; Potter D.A.
Abstract:
We examined the effects of supplemental food sources on parasitism of turf-infesting white grubs (Coleoptera: Scarabaeidae) by tiphiid wasps (Hymenoptera: Tiphiidae). Survival of spring active Tiphia vernalis Rohwer and late summer active Tiphia pygidialis Allen, parasitoids of Japanese beetle, Popillia japonica Newman, and masked chafer, Cyclocephala spp., grubs, respectively, was significantly increased when wasps were provided with 10% sugar water in the laboratory. Presence of a grub for host feeding did not affect wasp longevity. Sugar sprays applied directly to turf were examined as a method for increasing grub parasitism rates. Large numbers of T. pygidialis visited turf sprayed with sugar water to feed. Parasitism of Cyclocephala spp. grubs by T. pygidialis was reduced in sugar-sprayed turf, but higher in turf plots located near sugar-sprayed turf. T. vernalis, which feeds on homopteran honeydew secretions, was never observed feeding on sugar-sprayed turf, nor did such treatments affect its parasitism of P. japonica in or near sugar-sprayed turf. Gardens of spring- or fall-blooming flowering plants were established and monitored to determine whether particular species might attract Tiphia spp. No T. pygidialis were observed feeding on flowers in fall-blooming gardens. Large numbers of T. vernalis were observed feeding on nectar from peony, Peonia lactiflora Pallas, in the spring-blooming garden. When replicated plantings of P. lactiflora were established in a stand of turf, parasitism of P. japonica was significantly higher near the peonies. Incorporating such nectar-producing flowers into a landscape may increase parasitism of P. japonica by T. vernalis.

(The full article is only available for a fee, but you may be able to find the journal at a university library and make a photocopy)

Here is a link that might be useful: abstract of article

This is very interesting. It really is! How wonderful of you to do all of this finding out.

I'm wondering what it means in practical terms, though. Now that I think about it, I'm starting to suspect that the adult beetles that swarm in writhing hordes on my raspberries and rugosa rose blossoms must fly in from somewhere else. So I could replace the entire lawn with peonies, and it probably still wouldn't help much. Sigh.

One thing I have noticed, though, is that if I'm at home and can go out several times a day to drown beetles, the total number of drowned beetles at the end of the day is less than if I only go out once in the evening to drown them. This seems to me to fit in with Professor Potter's findings on Japanese beetle traps: bigger wads of beetles means more pheromones means more beetles attracted from wherever the beetles come from means more damage.

Here is more information: Prof. Potter doesn't think that the Tiphia vernalis wasp will ever be very effective at controlling Japanese Beetles, because the wasp has "intrinsically low fecundity", in other words each female wasp lays no more than a few eggs per day (or only 100 to 200 eggs total in her lifetime, since the adult wasps are active for one to two months), even when presented with all the food they can eat and a large excess of Japanese Beetle grubs to attack. Therefore noticeable JB suppression is not expected from releasing Tiphia vernalis in your yard, planting their preferred nectar or other host plants, or anything else to do with Tiphia vernalis.

Another direction quote from Prof. Potter:
>> Regarding massive plantings of peonies and popular articles, I'm not sure I'd be ready to make a recommendation that this tactic will pay substantial dividends, as the increase in parasitism we saw was modest, and confined to the area near the plants. Tiphia vernalis' main food source seems to be honeydew from aphids and soft scale insects. The adults are very tree-oriented insofar as mating and food; e.g., we could attract them by the hundreds simply by spraying 10% sugar water on oak foliage bordering rural golf courses (where insecticide use was minimal) in late April and May. So I think that peonies and possibly other nectar sources that might be provided in small gardens provide only a fraction of the carbohydrate diet these wasps partake of between bouts of searching for victims (grubs) on which to lay there eggs. Likely any neighborhood with a diversity of woody plants would already have plenty of carbohydrate food sources. More likely the impact of these wasps is limited by their intrinsically low fecundity (even in the lab, where grubs are provided in excess, they lay only a few eggs per day). I view them as one component of a whole suite of predators, parasites, and pathogens that help suppress JB populations, with perhaps no one agent alone providing consistent control. Prof. Potter goes on to mention that parasitic microorganisms play an important role in JB population control and some of these microorganisms haven't been thoroughly investigated. For example "certain protozoa (e.g. Ovavesicula species) .. cause a debilitating disease" of female Japanese Beetles. "Not much is known about those pathogens and they are not commercially developed." Perhaps this is the most promising area for future research in biocontrol of JBs.

To summarize what I have read (Prof. Potter and other sources),

MILKY SPORE - Controlled studies have shown that milky spore is not effective in reducing JB grub populations. And even if you could reduce the grub population in your own yard, that would have little effect on the number of adult beetles that show up to feed on your garden plants, because the adults fly a long distance.

BENEFICIAL NEMATODES - Not as well studied as milky spore, but the point about grub reduction in your own yard vs. adult beetles flying in from elsewhere obviously applies to this agent also. In addition, cost becomes prohibitive for treating a large area.

TIPHIA VERNALIS (PARASITIC WASP) - They're already here, and doing what they can to parasitize beetle grubs, but their impact is limited because their "strategy" as a species is to lay a relatively small number of eggs and feed lightly on the JB grub population. You don't need to do anything special to encourage them, but avoid using broad-spectrum chemical insecticides (that are harmful to many species of beneficial insects).

PHEROMONE TRAPS - Bad idea, they attract more beetles to your yard and increase damage to your plants. Even massive numbers of traps don't help! "For example, they ran 5000 traps at the Louisville Airport for a number of years to try to reduce hitchhiking beetles getting on aircraft (to the West Coast) but finally gave up because they saw no measurable impact."

The only proven effective "IPM" control measure (if we agree that highly toxic, broad spectrum insecticides such as Sevin are ruled out as IPM because of the "collateral damage" to beneficial insect populations) is, unfortunately, plant selection and replacement. In other words, if you're fed up with seeing your Linden tree "skeletonized" by JBs each summer, your best option may be to remove it and replace with a JB resistant tree such as beech, maple, redbud, etc.

Another quote from Prof. Potter: "Here in KY, where JB was in outbreak status during the 1980s and early 90s, we tried to emphasize plant selection as the primary means of defense. Here, every summer you can spot all the linden trees from a distance because they invariably are defoliated and brown. Replacing a purple-leaf plum with a copper beach or Forest pansy redbud, replacing a Radiant crabapple with a resistanyt cultivar such as Harvest Gold or David, or replacing a sassafras or linden with a red maple solves the problem with JB defoliation of landscape trees."

Pretty interesting stuff. Thanks for sharing!!
I have been told the same as what your Prof says about pheromone traps when inquiring about using them to deal with mtn pine beetle.

Has anyone ever looked into japanese beetle deterrents? If pheromone traps just attract more beetles, it would make sense to find something to deter them (analogous to deer repellents, although they are only of limited benefit). However, if there exists such a thing as beetle a deterrent, I'd sure like to give it a try.

Carl