The Dutch winter has been exceptionally gentle to this point and there aren’t any indications that this can change quickly. And that’s to the benefit of the oak processionary caterpillar. A gentle winter ensures a larger likelihood of survival of the eggs of the oak procession butterfly, explains director Bastiaan Meerburg of the Knowledge and Advice Center for Animal Pests (KAD).
“Normally the eggs hatch in April. If the weather stays so mild, that could happen in March. Whether there will be more caterpillars is difficult to predict. However, the peak that last year will be 15 June, push forward a month “, Meerburg says.
The animal pest skilled nonetheless holds the mandatory blows, as a result of though a frost interval shouldn’t be within the offing, in response to meteorologists, for instance, a chilly interval should still arrive in February. “You don’t know what the winter will do,” he says.
Nevertheless, in response to him, that is “the moment” when municipalities should make a plan about how they are going to deal with the oak processionary caterpillar this yr. “Last year some municipalities were completely surprised, that is now no longer possible. They must have thought that now.”
Municipalities took motion too late
The nuisance attributable to oak processionary caterpillar final summer season was 3 times as nice because the yr earlier than. Tens of 1000’s of individuals reported to medical doctors and hospitals with irritations to the pores and skin, eyes and lungs.
Many municipalities solely determined to fight the nuisance attributable to the caterpillars in May or June. The biggest struggling had already occurred at the moment, as a result of the caterpillars had been already totally grown by then and 1000’s of hairs – which trigger itching in individuals – had already been shed.
This yr, municipalities won’t need to make the identical mistake. The variety of municipalities which have made preparations has subsequently elevated in comparison with final yr, the NOS in December based mostly on a tour of dozens of municipalities.
The sucking of oak processionary caterpillars was final summer season a generally used management technique. (Photo: Pro Shots)
Knowledge platform expects many caterpillars this yr
The Knowledge Platform for Oak Processionary Caterpillar, an initiative of the Ministry of Agriculture, Nature and Food Quality, together with KAD, has tried to establish what the so-called “pest pressure” shall be in 2020. These are a very powerful conclusions:
- Fewer oak processional butterflies have flown out than a yr earlier. However, it’s nonetheless the second largest quantity since 2012.
- The explanation for this lower is unclear. Possibly that is because of the energetic management of caterpillars final yr.
- It is feasible that many caterpillars have crawled into the soil because of the warmth and can reappear in the middle of the oak procession season.
- The latter can cancel out the impact of preventive management. Also final yr the platform all of a sudden noticed outbreaks in locations the place good management had taken place.
- Conclusion: the Knowledge Platform Oak Processionary Caterpillar expects a “large pest pressure” based mostly on the variety of butterflies noticed this season. This plague can improve if caterpillars additionally emerge on a big scale.
Eggs barely seen with the bare eye
KAD helps municipalities to stop caterpillar management. They may also seek the advice of Processionary Knowledge Platform. According to Meerburg, the most typical means of this preventive management is to spray with nematodes. “This is a form of biological control, in which the nematodes plant a bacterium in the larva of the egg.”
Preventive removing of the eggs is unnecessary, in response to him. Although the eggs have been ready in ticking timber since autumn, they’re barely seen to the bare eye.
Finally, Meerburg hopes that municipalities are “aware of their responsibility”. “I would find it strange if they had hardly made any preparations at places where they were inconvenient last year,” he says.