The late maturation of wasp nests in 2016 and the relatively late start to winter suggests that a high proportion of queen wasps will survive into 2017. The reasonably cold winter with few intervals exceeding 10°C appears to have favoured queen survival and initial reports from bee keepers and pest controllers is that wasp queen numbers are higher than in previous years. There is therefore the potential for a high wasp season but this is dependant on weather over the Spring and Summer periods.
Mild winter conditions and early nest maturation in 2015 resulted in fewer queen wasps surviving into 2016. Less favourable Spring conditions and a warm wet summer resulted in delayed maturation with wasp nests not maturing in some regions until late November. Wasp activity during the late summer months was significantly depressed because of an extended hunting phase.
Late wasp nest maturation in 2014 coupled to a relatively cold winter resulted in elevated numbers of queens surviving into 2015. The favourable Spring and early Summer conditions resulted in high wasp activity across most of the country and wasp populations recovered completely from the lows experienced in 2012.
The winter for 2014 was relatively mild suggesting that queen numbers would not be high for 2014. Severe flooding in parts of the UK knocked back wasp populations in certain regions especially of Vespula germanica which prefers to nest in the ground. Otherwise other parts of the country witnessed recovering wasp populations. Warm wet weather provided for lush vegetation with larger nest than usual and a slightly later wasp season which kicked off late August.
Predictions for the 2013 season were difficult.
2012 witnessed the lowest wasp population levels since WaspBane began monitoring wasp populations in 2001. A number of coincidental factors combined to create catastrophic pressure on wasp numbers. In 2011 the wasp mating season was adversely impacted by strong gales which suppressed wasp colonies just as they were about to produce their sexual progeny. As a consequence there was no concerted mating event and both queens and drones were released sporadically leading to high numbers of queen mating failures. So whilst a reasonable number of queens survived through until 2012, many of them had not mated successfully and were unable to produce viable colonies. Moreover, the cold and wet spring conditions of 2012 with suppressed temperatures hovering at 10°C up until May resulted in queens dribbling out of hibernation over a period of 2 months instead of the usual 2 weeks around March. Many wasp colonies therefore failed to achieve critical mass before the autumn mating period which was additionally suppressed through poor weather. As in 2011, 2012 did not experience a concerted mating event and queen numbers appear to be low. As a consequence, 2013 appears to be starting from a low base. The winter conditions for 2013 appear to have favoured wasp hibernation and it appears that this may have improved the number of surviving queens and so may help to restore wasp population numbers in 2013. Indications in May suggest that a reasonable number of Vespula germanica queens have survived the UK winter and there is now a growing expectation that wasp populations will increase compared to 2012 but generally speaking, there is still an expectation for a low wasp season for 2013.
2012 UK Historical;
Queens started emerging from hibernation from the second week of March 2012. However, inclement weather over April and consistently low diurnal temperatures had suppressed temperatures in north facing sanctuaries sites. Stone and brick work in particular had remained cold and damp with temperatures depressed below 10°C up until about the second week of May. After then temperatures rose with the last of the hibernating queens finally emerging during the third week of May. The late emergence of queens over a protracted period meant that wasp nests failed to mature by the end of July particularily because consistent wet weather supressed hunting and colony development.
Persistant heavy rainfall and extensive localised flooding had a significant effect on Vespula germanica which as a low level predominantly ground nesting wasp has seen its numbers plummet. As a consequence most nuisance wasp activity came from Vespula vulgaris and some of the less frequently encountered Dolichovespula species, in particular Dolichovespula media.
Pest controllers reported very low numbers of call outs to treat wasp nests and many of these were quite late in the year. It is not entirely clear whether this was down to people remaining indoors due to inclement weather and latterly the Olympics and therefore not being exposed to wasps or because wasp numbers were genuinely down against average. Pest controllers did report an uplift in call outs which seemed to coincide with the end of the Paralympics. Certainly, wasp nests were not as well developed as they should have been meaning that worker wasp numbers remained down on the same period. It is also clear that the number of colonies was also significantly down. The first wasp nests to mature matured in late September, i.e. 8 weeks later than normal. Reports of nests maturing as late as November were received meaning that there was no concerted mating event and it is highly probably that many queen wasps did not mate properly. The late nest maturation in November did however favour queen survival into 2013.