Combating Wasps: Recommended Practices tor Beekeepers

New Zealand Journal of Agriculture, Volume 79, Issue 5, 15 November 1949, Page 457

Combating Wasps: Recommended Practices tor Beekeepers

FOUR years have passed since wasps of the species Vespa germanica were first discovered in the Waikato district. In this article C. R. Paterson, Apiary Instructor, Department of Agriculture, Hamilton, describes the experience gained in recent years in combating the wasps and recommends certain apiary practices which beekeepers must adopt to protect hives against the pest.

SUFFICIENT time has now elapsed *•-' to enable first-hand information to be collected and for the position as to the extent wasps constitute a menace to the ' beekeeping industry to be reviewed. In an analysis of the exact position regarding the activity .of wasps it is necessary to consider the locality in question and the incidence of infestation, or the conclusions reached may be wrong. Many beekeepers who are asked to what extent thev consider wasps are harmful to beekeeping will say frankly that they have not been worried by them in the least. Others located in the same district are considerably concerned at the attention the wasps give their colonies.

What, therefore, is the reason for this difference in experience? There appears little doubt that the destruction of active nests is a very definite means of reducing the number of flying wasps in a particular district. In clean, open country nests are soon discovered, as people generally are on the alert. This means that apiaries in such areas receive very little attention. Yet apiaries only a mile or so away may have almost as many wasps as bees flying around at certain times

of the year. Apiaries so affected are generally very close to large, scrubcovered gullies or weed-infested areas, and where these conditions exist it is almost impossible to locate nests. This means that nests are able to build up to maximum strength and by autumn large numbers of wasps are searching for suitable food. How Wasps Affect Beekeepers From January onward wasps become actively interested in sweet substances such as fruit juices, jam, and honey, and honey houses become a centre of attraction. Buildings that are considered bee proof will not keep out wasps, which have the determination and

ability to force their way through openings through which a bee would never attempt to pass. Where large numbers of wasps are flying round in the honey house when honey is being extracted or, especially, when it , is being packed the beekeeper is faced with a major problem. With characteristic persistence wasps attack relentlessly hives which are not able to offer sufficient resistance. On many occasions it may be possible to see bees ejecting numbers of wasps, but if the beekeeper maintains a watch he will notice that wasps are continually evading the guards and gaining entrance to the hive. It is amazing how wasps hover round and, as soon as an opportunity occurs, enter the hive. Bees would have a reasonable chance of coping with wasps but for the fact that the latter appear to have a degree of intelligence which they use to good purpose. As bees

form themselves into a partial cluster at night or during unsettled weather, wasps find it comparatively safe to enter hives early in the morning or late in the evening, when guards are mostly off duty, and on wet days it is possible to see wasps flying in and out of hives without encountering much opposition. Under these conditions colonies short of stores very soon find themselves on the point of starvation and, when this state has been reached, very little can be done to save the hives, except perhaps to remove them to another site. It is in the establishment of nuclei during the autumn that beekeepers are most likely to be seriously affected by wasps, if all wasp nests close to hives are not destroyed. Wasps (workers and drones) give newly-made-up colonies a great deal of attention and there have been many in- . stances where nuclei have been wiped out. Beekeepers’ Experiences Checking the actual experiences of beekeepers has been somewhat difficult because of the delay in receiving reports. There is no doubt, however, that many beekeepers have lost numbers of nuclei during the past few years. In certain areas it is possible to find wasps intermingling with bees . in the hives. A case involving the loss of approximately 34 hives last winter has been reported. x It is believed that the apiary concerned had received the normal autumn management and about 4

combs of honey had been given to each hive as supplementary stores. An inspection of the particular apiary in April showed that wasps were flying round in large numbers and 4 hives were almost robbed out. These were not weak hives, as they still had as much as 6 combs of brood. The bees in all the other hives were on the alert; bees were right across entrances and at this particular time any invading wasp was dealt with strenuously. Besides the wasps concentrating on the weakened hives others could be seen investigating every crack in hives and lids. It was recognised that the increased activity of the bees in defending their hives would mean a serious depletion of winter stores. In this apiary wet supers had been placed out and these may have been responsible for attracting such a large force of wasps. The apiary was on the edge of a large gully in which it would be impossible to locate and destroy wasp nests.

Suggested Methods of Control It is unfortunate for beekeepers that it is not possible by using screens to prevent wasps from invading honey houses and beehives; wasps will crawl through a smaller opening than a bee so that a wire excluder is impracticable. Until research workers, who are now making investigations, are able to find more effective control methods the following appear to be the best precautions that can be taken: — 1. The beekeeper should encourage all occupiers of property close to the apiary to locate and destroy as many wasp nests as possible. 2. When necessary the beekeeper should destroy nests himself - when they are reported. 3. Hive equipment should be kept thoroughly sound; badly-fitting lids and warped supers should be discarded. 4. A high standard of cleanliness around the apiary should be maintained; honey or odd pieces of comb should not be left about. 5. Entrance guards should be placed on hives as soon as wasps appear to be troublesome. In warm districts it may be necessary to allow further ventilation by placing an empty super on top of the hive.

6. Extracted combs should not be put out in the apiary for the bees to clean out.

7. Nuclei established in the autumn should be placed out in apiaries where wasps are not likely to be troublesome.

8. In wintering down colonies allowances should be made for additional supplies of feed honey— is not only the amount of honey robbed by the wasps which has to be taken into account; bees themselves consume a considerable amount while continually on the alert to defend their hives. The evidence this season has indicated that where wasps have become well established beekeepers face a definite problem. The menace can be combated only by co-operating with the public in a campaign of destruction, including a diligent search for hibernating queens and established nests.