Frisch, K. von. 1943. Versuche uber die Lenkung des Bienenfluges durch Dufstoffe. [Experiments on directing bee flight by odors]. Die Naturwissenschaften. 31 (39/40), 24 Sept. 43):445-460. [Translation by W.J. Nolan]

EXPERIMENTS ON DIRECTING BEE FLIGHT BY ODORS [Exerpts as published by von Frisch, in translation - bold emphasis mine]

Not infrequently both beekeeper and agriculturist have wanted to induce bee visitation to a particular plant in order to increase the honey crop or the yield of seed. Investigations on the sense of smell and on the "speech" of the bee for more than 20 years form the basis of efforts to direct the flight of the bee at will .... On finding a source of nectar, the discoverer alerts her hive mates ... causing them to fly out and hunt around and ... to scour their whole flight range in search of the odor which they have perceived on the returned dancers.

How long odors taken on by a bee's body remain recognizable by other bees is a point of special interest.

... bees fed at a scented location send their hive mates out after this odor. This was done by Russian bee investigators [e.g., Bugin, Kapustin, Komarov, Savitski, Sorokin,] who used the idea chiefly for increasing bee flight to large tracts of red clover.

Let us continue, then, with my idea of making a practical application of the dances of the bee. Accordingly, we give the bait food during the day, the time of flight.

1. Can outside feeding be replaced by feeding inside?

As a general rule the bees visited the check cardboards only briefly and rather transitorially while they displayed an evident interest in the odor cardboard through hovering around it longer, until they flew away from its empty dish as if with sudden determination ....

An appreciable degree of directed flight can be obtained, therefore, by inside feeding in a scented atmosphere.

...weather conditions, among them wind direction assuming a special role...

We limit ourselves here to the conclusion that hive feeding in a scented atmosphere can be as effective as outside feeding.

2. Can a scented atmosphere be replaced by scented sugar syrup [in the field]?

... the giving of scented sugar syrup by a bee to its hive mates may be an especially favorable way of communicating the "odor word."

It was an enchanting sight to watch the bees, often in formation flight just above the ground, heading towards the lavender cardboard against a gentle breeze.

Their delay and less frequent coming was, as a matter of fact, influenced by the wind direction; in contrast with the other two experiments, it was directed towards the hive only from 11:13 A.M. to 11:26 A.M. on September 2.

This temporary, favorable current of air was clearly expressed by an increased visitation (fig. 8).

3. Can odor coming directly from the flower be replaced by the odor from an extract of the flower in sugar syrup?

4. The use of fresh blossoms in the hive.

Feeding with 100 cc of scentless sugar solution (1:1) scarcely increased the visitation in two experiments.

From July 29 until August 14, 1942, only odorless sugar syrup was given. In this period 36 checks yielded an average of a little more than one bee (average 1.3) for the whole marked [observation] strip.

In 51 checks, the average number of visitors to the observation strip after beginning the odor feeding (from August 15 to 29) was 29 bees. The number had risen, therefore, 22-fold.

After stimulative feeding with 100 cc. of plain odorless sugar syrup about 11 A.M., things in the gully were as before (in 3/4 hour observation 1 honeybee, 45 bumble bees)...

I now wanted to see whether the visitation of the blossoms could be increased still further through feeding with sugar solution scented with thistle according to the Russian method. ... The average flight to both places on this and the following day was 45 honeybees and 16 bumble bees per 1/4 hour for 3 3/4 observation hours.

The stream of newcomers is very much more lively in case of the use of strongly scented blossoms. ...the more intense the flower odor the better will be the result.

5. Experiments with use of a flower odor other than that of the flower to which the bees are being directed.

6. Time and manner of feeding.

7. Limits of the Method

From the observations up to now, it is to be expected that one can accomplish several things through a proper method for baiting by odor in sugar syrup: the speedy visitation of a definite bee plant, an increase in intensity of work by the bees as well as an increase in the number of flights; and a lengthening of their hours of work.

Under certain circumstances, especially in spring, the drawing power of many nectar flows are so great that honeybees resist even the attraction of concentrated sugar solutions. Naturally, under these conditions direction by odor is rendered difficult. Perhaps the remedy is the employment of colonies to which young bees have been added.

8. Experiments on baiting by odor carried out in the summer of 1942 through the Reichsfachgruppe Imker.

Summary of the Results [entire summary, not exerpts]

1. In feeding a group of bees at a scented base, their hive mates, alerted by their dances, scour the locality in all directions in search of that odor. Feeding inside the hive in a scent-laden surrounding can be just as effective as feeding outside. Nevertheless, every odor must be tested by itself to ascertain its effect.

2. Feeding with scented sugar syrup inside the hive can likewise be of excellent effect. In this case the result is dependent on the properties of the scent material and cannot be told in advance by any general rule.

3. Whether simply laying fragrant blossoms in sugar syrup will result in a scented solution which smells like fresh flowers to the bee can not be foretold in any instance. It succeeds in the case of thistle (Cirsium oleraceum) even if the smell does not correspond completely, perhaps, with the natural odor of the flower. it does not succeed in the case of summer rape.

4. Instead of giving scented sugar syrup, the feeder in the hive can be surrounded with fragrant blossoms. Measures must be taken, however, to prevent the blossoms being carried out by the bees. In the case of red clover the visitation can be increased in this way by 22-fold; in the case of potherb by more than 12-fold. Through these measures the intensity of the work of the bees is also increased and their working hours lengthened.

5. Visits to odorless or nearly odorless flowers can be induced by adding the bait odor of another flower to sugar syrup fed in the hive, coupled with spraying some of the syrup on the odorless or nearly odorless flowers outside.

6. In night bait feeding, the bees which fly to the flowers the next morning are apparently the very bees which were fed and trained to the odor, but, in the case of day feeding during the hours of flight, it is the hive mates aroused through the dances which are the first visitors to the flowers. It is still a question as to which time of feeding and which way of giving the sugar syrup are the most favorable.

7. Where no honey flow exists, guiding by odor is pointless. It is made more difficult if there is strong competition from other rich sources of nectar.

8. Preliminary experiments on a large scale, carried out through the Reichsfachgruppe Imker in different parts of the country, brought about a considerable increase in the honey crop, partly through training to odor, in the case of several cultivated and wild plants. An increase in the number and an intensification of the visits to the flowers was observed several times in spite of lack of an adequate method for baiting. An increase in the seed harvest can be anticipated on this account although it has not yet been realized.