Mineral Oil as an Alternative treatment for Honey Bee Mites Part I (May 1999)
Dr. Pedro P. Rodriguez

Methods and Application and Test results
With the kind permission of the author Dr. Pedro P. Rodriguez
Dr. Veterinary Medicine, U. P. 1962
Retired GS-13 United States Department of Agriculture
Retired United States Army Colonel

Parasitic bee mites represent a formidable threat to susceptible honey bees of the Apis mellifera species. Destruction of most feral colonies and a high percent of domestic bees has alarmed the scientific community worldwide giving rise to teams of investigators studying various forms of treatment to combat them. Because of the bees' vulnerability and potential contamination of honey, the number of substances that can be utilized for that purpose are few and restricted by law. Mites have developed resistance to fluvalinate increasing the need for alternative methods of treatment. Food grade mineral oil, FGMO, is assayed in search of a bee friendly, environmentally friendly and cost effective method of treatment for bee mites.

Although mites have been known as parasites of honey bees for nearly a hundred years, their notoriety is recent in the western hemisphere. In Asia, their original habitat, parasite and host have achieved an optimum state of coexistence. Many researchers agree that one bee species, Apis cerana, has developed its own form of protection against the mites, through individual and colony hygenic habits. In this species, bees groom themselves to remove adult mites and discard infested bee larvae (Peng et al, 1987) thus keeping the mite population low. Spivak and Gilliam, 1998, give high praise to the value of hygenic behavior in mite and disease control citing an abundance of literature on this subject (33 authors). Other contributing factors found in this bee species are: mites preference for drone larvae (Koeninger, 1981); temperature and climate (Eischen, 1987). On the contrary, it is generally accepted that European bee species lack some of the factors observed in A. cerana species (Faucon, 1991). Spivak and Gray, 1998, reported that in the United States hygenic behavior is estimated to be found in only about 10% of managed colonies, fact that contributes to the vulnerability of managed bees.

According to general opinion, many factors have combined in favor of the mites. In Europe, generalized skepticism by beekeepers about the mites' harmful potential contributed to spread of the mites from middle European countries to the southern tip of the Iberian Peninsula with an amazing rate of dissemination. In the United States, Varroa made its initial appearance in the state of Florida in 1987 and has spread practically throughout the entire continent within a decade destroying in its wake nearly 100% of the feral bee population and a very high per cent of managed bees (Sammataro, 1997). Several researchers have indicated that misuse, misinterpretation of instructions about Apistan and lack of knowledge about the genetics of bee mites has led to development of resistant generations of mites in the United States and abroad. Resistance to fluvalinate has been documented in Italy (Faucon et al, 1995; Lodesani et al, 1995; Milani, 1995). In the United States, resistance to fluvalinate has been verified in the states of Florida and South Dakota (Eischen, 1998) and rumored identified in as many as six states.

Material and Methods
A. Materials

  1. Standard Langstroth type hive body chambers and medium size supers.
  2. Penreco Food grade white mineral oil.
  3. 14 1/2" x 18" waxed paper or freezer paper.
  4. 1 1/2" x 10" waxed paper strips.
  5. Calibrated eye dropper.
  6. One pint bottle dispenser provided with a wick and mounted on a Luan wood stand.
  7. Portable propane insect fogger.
  8. Tobacco leaves and stems.
  9. Penreco Food Grade White Mineral oil/sugar emulsion patties.
  10. Bee colonies of similar strength.

 Methods of Application
Several methods of application of food grade mineral oil have been tested in a period of time spanning from 13 April 1996 to 21 November 1998.

1. Laboratory
Fiftyfive mites collected from eleven colonies in a wide mouth glass jar and driven a short distance for testing. (Mites were removed from the jar by allowing them to crawl on tooth picks).

  1. 10 mites placed on a glass slide and gently dabbed with a Q-tip soaked with FGMO.
  2. 10 mites placed on a top bar previously smeared with FGMO.
  3. 10 mites placed on a sheet of waxed paper smeared with FGMO.
  4. 10 mites placed on a "sticky trap" prepared with waxed paper smeared with FGMO.
  5. 10 mites placed in another jar smeared with FGMO.
  6. 5 remaining mites allowed to stay in original jar. Top edge of jar was smeared with (OFF) insect repellent to keep mites from escaping.

2. Field Tests

  1. sheets of waxed paper smeared with FGMO placed on the bottom boards.
  2. strips of waxed paper smeared with FGMO inserted between frames.
  3. 2.5 cc FGMO placed on top bars in a continuous bead. (previously reported on the internet).
  4. FGMO in one pint bottle dispenser with stand placed on top bars.
  5. portable propane insect fogger.

1996-1997 Trials
i) Twenty five Italian bee colonies (twenty test colonies and five control colonies) of similar characteristics and size. Bees were distributed in three  sites at least 16 miles apart. Initial mite counts were performed on each colony by uncapping 100 capped cells within a 3" x 4" inch homogeneous area of brood combs.

1998 Trials
ii) Five test sites were established in cooperation with area beekeepers. Colonies utilized were of similar characteristics and size, forty colonies being last year's bees. All colonies consisted of a full body brood chamber and one medium sized super (1) and additional supers added as needed for stored honey. All colonies were numbered and control colonies were selected at random at each site. Initial mite counts were performed by uncapping 100 capped cells within a 3" x 4" inch homogeneous area. Test colonies were treated every two weeks with FGMO applied with a Burgess brand portable propane insect fogger. Beginning on 5 July 1998, all colonies were smoked with tobacco smoke and mites were collected on "sticky traps" on the bottom boards.

(1) Several swarms of unknown origin collected during the Spring and Summer of 1998 were added to project at site # 5 and treated with FGMO.

Distribution of test colonies:

  • Site No. 1.
    Ten test colonies; three control colonies. The number of test colonies at this site diminished as site owner joined the colonies that became weak.
  • Site No. 2.
    Four test colonies; one control colony.
  • Site No. 3.
    Three test colonies; one control colony.
  • Site No. 4.
    Six test colonies; three control colonies.
  • Site No. 5.
    Two colonies owned by site owner. Seven additional colonies developed from swarms. Colonies were divided into 7 test colonies and two control colonies.


A. In vitro tests.

  1. mites died within one minute.
  2. mites died within two minutes.
  3. mites died within two minutes
  4. mites died within two minutes.
  5. Mites died within two minutes.
  6. mites died on the 4th day.

B. Field tests

Penreco White Food Grade Mineral Oil (FGMO).

a. 27 April 1996: Waxed paper sheets 14 1/2 wide by 18 inches long coated with mineral oil (one tablespoon per sheet) were placed on bottom boards of twenty colonies. Five colonies randomly selected were left untreated for control purposes. Inspection of waxed papers on bottom boards revealed a varied number of mites (19 to 108). The number of mites found on these sheets is not accurate since the bees chewed and removed part of the paper before mites were counted.
Capped cell mite count: 36% in treated colonies.
Capped cell mite count: 54% in control colonies.

b. 11 May 1996: Waxed paper sheets coated with FGMO (one tablespoon per sheet) placed on top bars between brood chambers and honey supers. (On 25 May 1996,
waxed paper sheets were replaced with freezer paper obtaining similar results).
Dead mites harvested on sticky trap 28%.
Capped cell mite count: 30%.

c. 6 June 1996 - 4 January 1997. Twentythree Italian race bees in Langstroth type hives (one brood chamber and one medium size super) distributed in three sites. Colonies were labeled with continuous numbers 1-23, (#'s 10, 13, 15, 18, 20, 23 randomly selected as controls (2)). Waxed paper strips coated with FGMO inserted between frames of brood chamber revealed the following findings. Strips were replaced every two weeks.
((2) All colonies utilized as controls died.) Capped cell mite counts at two week intervals. 13%, 9%, 8%, 6%, 5%, 4%, 3,%, 2%, 2%, 0%(3), 0%(3), 0%(3)
((3) There was no brood present in the last three colonies listed.)

d. In the Spring of 1997, the form of application of FGMO was changed from waxed paper strips to a continuous bead of oil spread on the top surface of the top bars. This form of treatment was applied to 23 colonies surviving from the precious year and some colonies formed from swarms strengthened with package bees and distributed in 3 sites. At first, the amount of oil was measured and applied with a graduated eye dropper, arriving at 2.5 cc of oil as a safe quantity. Later, it was applied with a bottle similar to a honey bear with a spout with an opening measuring 1/16" in diameter. During the course of application, it was determined that it was not necessary to spread the oil, the bees spread it as soon as they walk on it. The following results were observed. Of the 20 colonies treated with FGMO, one absconded and two were small and weak and died due to pilferage. Three colonies used as controls died. Capped cells examined revealed mites in both drone and worker bee cells. Mite counts varied from 54% to 4% during this test period.

On Sunday, August 24, 1997, a new method of application of FGMO was initiated on 24 colonies (remaining colonies from previous tests and collected swarms). In this test, oil was applied by means of pint bottle dispensers. See diagram. Although promising, this form of application was discontinued because the bees did not come in contact with enough oil for it to be effective. There was not enough time left to make modifications needed since it was started late in the season.

mineral oil

f. Application of FGMO with the Burgess Portable Propane Insect Fogger.

Site No. 1: Ten test colonies and three control colonies.
The number of colonies at this site diminished as participant joined the colonies that became weak. Significantly, mite counts nearly doubled in the colonies that were joined together. Conversely, in colonies that remained intact, mite counts diminished with treatment or showed very slight increase.

  • 72 mites during first count to 134 mites counted after joined together.
  • 40 mites during first count to 150 and 259 after joined together.
  • 92 mites during first count to 206 and 580 mites in subsequent counts.
  • 27 initial mites counted followed by 60 mites and 35 mites in subsequent counts.
  • 67 initial mites counted followed by 60 mites and 85 mites in subsequent counts.
  • 23 initial mites counted followed by 64 mites and 47 mites in subsequent counts.

One of the control colonies died and one colony absconded.

Site No. 2: Four test colonies and one control colony. (Colonies had two supers).
Although two of the test colonies developed AFB during the course of the test, results were fairly consistent with results obtained at sites 3, 4, and 5.

  • 3 initial mites counted followed by 12 mites and 17 mites in subsequent counts.
  • 4 initial mites counted followed by 9 mites and 13 mites in subsequent counts.
  • 2 initial mites counted followed by 4 mites and 23 mites in subsequent counts.
  • 5 initial mites counted followed by 9 mites and 56 mites in subsequent counts.

Control colony: 2 initial mites counted followed by 21 mites, 39 mites and 1004 mites when submitted by the owner to an Apistan knock-down test at the end of the test period.

Site No. 3: Three test colonies and one control colony.

  • 3 initial mites counted followed by 14 mites and 17 mites on subsequent counts.
  • 5 initial mites counted followed by 7 mites and 12 mites on subsequent counts.
  • 6 initial mites counted followed by 13 mites and 3 mites on subsequent counts.

Control colony: 8 initial mites counted followed by 30 mites and 195 on subsequent counts. This colony died in September.

Site No. 4: Six test colonies and 3 control colonies.

  • 3 initial mites counted followed by 19 mites and 24 mites on subsequent counts.
  • 0 initial mites counted followed by 3 mites and 4 mites on subsequent counts.
  • 2 initial mites counted followed by 26 mites and 23 mites on subsequent counts.

Control colony: 3 initial mites counted followed by 35 and 109 mites.(4)

  • 2 initial mites counted followed by 10 mites and 22 mites on subsequent counts.
  • 11 initial mites counted followed by 16 mites and 27 mites on subsequent counts.

Control colony: 4 initial mites counted followed by 19 mites and 90 mites. (4)

  • 2 initial mites counted followed by 3 mites and 22 mites on subsequent counts.
  • 6 initial mites counted followed by 25 mites and 108 mites. (4)

(4) All three control colonies developed chalk brood disease and died when robbed by their neighbors.

Site No. 5: Two original colonies and seven additional colonies developed from swarms.

Tests at this site began in mid summer when participant joined test program with two colonies, one test and one control. All but one of the swarm colonies responded well to FGMO treatments.

  • 11 mites initial count followed by 13 mites and 13 mites on subsequent counts.
  • Control: 33 initial mites counted followed by 57 and 100 mites subsequent counts. (5)
  • 7 initial counted followed by 14 on subsequent count.
  • 33 initial mites counted followed by 57 on subsequent count.
  • 24 initial mite count followed by 73 on subsequent count.
  • Weak, re-queened, absconded.
  • Queenless, re-queened, absconded.
  • Died.
  • Absconded

(5) Control colony became weak, diseased, robbed and died.

On 21 November 1998, 21 colonies were treated with 40% FGMO/sugar emulsion patties at sites 3, 4 and 5 in an effort to assay the feasibility of continued treatment with FGMO during the winter without recurring to chemical treatments. Efficacy of this form of treatment will be assayed next Spring and results made available in a follow up report.

These tests and those of other investigators indicate that oil may be an efficient alternative form of treatment for bee mites. The body of bee mites is flat thus having a high ratio of surface volume (factor also used by Italian researchers) of bee mites. Also, a study by British researchers indicate that female mites control gaseous exchange through adjustment of components of their respiratory system. These characteristics together with the bee/mite body size differential ratio make bee mites vulnerable to treatment with oils without harming the bees. Applied with the Burgess Portable Propane Insect Fogger, mineral oil is delivered in microscopic particles averaging 15 microns in diameter dispersing the particles through the entire hive in fog form.

The microscopic size of the particles is believed to play a very important role in the use of FGMO as an acaricide. In this form, the oil penetrates the respiratory system of mites, blocking it and causing death by suffocation. Most importantly, it appears that mineral oil applied in this form is also effective for the treatment of tracheal mites since the oil penetrates the respiratory system of the bees, exposing the mites to the effect of the oil as it does to Varroa mites. Continued dissection of bee tracheas revealed total absence of tracheal mites in test colonies. These findings are consistent with those of a beekeeper in the Canary Islands (Spain) utilizing mineral oil for treatment of tracheal mites. The beekeeper wrote indicating great degree of effectiveness of FGMO for that purpose.

Initial phases of tests with mineral oil proved labor intensive, reducing the allure of mineral oil as an alternative treatment. However, when applied in fog form the procedure becomes fast, easy and economic requiring five seconds per hive and less than one gallon of oil for the entire year. The fogger is not a complex machine. It is easy to operate by bee yard workers, facilitating its use by individual and commercial beekeepers. Thus, achieving one of the goals of the last test period, to evaluate a cost effective method of application of mineral oil as an acaricide.

In large size colonies that require larger amounts of oil fog, the bees may become agitated but never aggressive contrary to initial reports across the nation indicating that the use of FGMO aroused aggressiveness. Mineral oil applied in this form does not seem to have deleterious effects on the hive population including queens, larvae and adults. Brood patterns are full and uniform and no signs of larval mortality were observed. Queens continued to lay unimpeded until late fall when last checked.

Test results indicate that at $4.50 per gallon and $65.00 for a fogger, mineral oil with its benign characteristics can be a reliable, environment friendly and cost effective alternative treatment for bee mites especially with increasing mite resistance to known chemical pesticides. FGMO is far more effective than what these tests reveal if judged by the number of mites remaining after treatments since treated colonies continue to be subject to infestation from neighboring control colonies. Also, FGMO would be more effective if it were to be applied in the form of fog combined with a continuous FGMO source such as FGMO patties or FGMO dispensers. This phase of combined forms of application is planned to begin next Spring.

Test sites
Ten colonies in the Great Neck area of Virginia Beach, VA (four colonies from previous years and six colonies developed from swarms). All colonies were arranged in linear display and labeled 1 -10.

mineral oil 2
Table No. 1 Uncapped Cells Mites
Count/10 Square Cms.(Suffolk, Virginia)

Twenty-nine colonies in partnership with Mike and Linda Campbell in Suffolk, VA. Test colonies included colonies from the previous year study, package bees and swarms. The Suffolk colonies were displayed in a square frying pan figure.

mineral oil 1
Table No. 2 Uncapped Cells Mites
Count/10 Square Cms.(Virginia Beach)

As in previous years, testing began on the second week of April and continued through November 1999. Monthly treatments were applied by means of FGMO spray applied with the Burgess Propane Insect Fogger and by Welt Upholstery cords soaked in FGMO/sugar emulsion.

mineral oil bug killer


  • FGMO sprayed with the Burgess Propane Insect Fogger
  • FGMO was applied in spray form once a month by blowing a steady stream of FGMO spray through the hive entrance.
  • The amount of spray applied and length of time varied according to the size of the colony, generally lasting 4 - 5 seconds per colony.

FGMO/sugar emulsion
TTreatment was performed applying two sections (40 inches long each) Welt upholstery cord previously soaked in FGMO/sugar emulsion. FGMO/sugar emulsion, provided by Penreco Technology Center laboratories in gallon metal containers, resembles Crisco vegetable fat in consistency and appearance. Because of its solid consistency, the emulsion required heating, (a propane burner at my home in Virginia Beach and the Campbell's kitchen stove in Suffolk). The Welt upholstery cord was cut in forty-inch sections, dipped in the melted FGMO/sugar emulsion which congealed on the cords as soon as it cooled. Two cord sections were removed from the dip vat and placed on all the top bars of the incubation chambers and on some supers in the colonies with multiple supers. The Welt upholstery cords were replaced approximately every thirty days, at which time the bees had chewed and removed most of them.

mineral oil string

mineral oil emulsion

Test results
Mite counts performed by opening larval cells revealed findings averaging between one and ten mites per hundred cells examined. Tests were conducted on days of treatment to minimize workload and harassment of the colonies. The last treatment in preparation for wintering was performed on October 24, 1999.


  • Observation of control colonies during past four years revealed the following data:
  • All untreated colonies died the same year
  • Population of control colonies diminished progressively by attrition, disease or fighting in defense of what remained of their colony
  • Almost invariably, all control colonies developed Nosema in the autumn
  • Adjacent test colony bees invaded and robbed control colonies by autum's end
  • When pilferage started in control colonies, randomly selected bees were colored-tagged on the wings. Colored-tagged bees were subsequently observed within other test colonies
  • Once the population decreased, control colonies abandoned house keeping.

Previous tests with FGMO in various forms proved to be successful, however the methods employed appeared, as time consuming hence considered not cost-effective. Application of FGMO in the form of emulsion was developed in the early years of FGMO testing, however various forms of application tried were unsuccessful due to mechanical problems. This year, use of Welt upholstery cord was adopted taking two factors into consideration: the physical characteristics of the emulsion and the housekeeping habits of honey bees. The Welt upholstery cord was easily coated with emulsified FGMO and the cords readily applied on the top bars with minimum effort. Honey bees were observed to initiate removal of the cord as soon as it was placed on top of the frames, thus becoming exposed to the mineral oil and its effect on the mites. Cords were chewed and shred within thirty days. (See attached photographs). Monthly combined applications of FGMO with the Burgess Portable Propane Insect Fogger and FGMO/sugar emulsion on 37 colonies greatly reduced labor and medication costs and kept the mite population at low levels (totally absent in some colonies), (See attached capped larval cell count charts). Past and present history of the behavior of honey bee mites tend to indicate that their existence within our honey bee colonies will be noticeable for years to come in spite of the combined efforts by those of us who toil to keep them in check. In light of these findings, addition to treatment, our work is being aimed at promoting the use of techniques to control their presence. We consider of special importance development of strains of bees that show tendency to resist mites. Hence our practice to utilize the housekeeping abilities of the bees in connection with removal of the Welt upholstery cord soaked with FGMO/sugar emulsion. In our FGMO treatment program we have several colonies that are four years old that not only have tolerated the presence of mites but that have thrived and produced high honey yields.


  • Four consecutive years of research with FGMO clearly indicate that untreated (control) colonies die within the same year.
  • onversely, colonies in the same group treated with FGMO have survived for four years.
  • No adverse effects by Pernreco's/DDrakeol, FGMO, have been observed on test colonies to queens, larvae or adult bee population during the past four years of testing.
  • Test results indicate that FGMO is an effective acaricide that can be utilized by small as well as commercial beekeepers for the treatment of honey bee mites in a cost effective manner.


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