The decline in the number of oak processionary caterpillars observed may be because the insects can spend a year, maybe even longer, underground. Researchers have recently seen an unexpected number of butterflies crawling out of the ground. This makes combating the plague more difficult, and nuisance may be greater, writes Nature Today.
A researcher from Kennisplatform Processierups saw this week that both males and females emerge that had burrowed into a test set-up last year. In other places, caterpillars have been observed that, with a short interruption above ground, have even been underground twice a year.
The fact that caterpillars remain in an extended diapause, a kind of hibernation, for a year or even longer, may explain why the Knowledge Platform caught 40% fewer butterflies in the caterpillar peak year 2019 than in 2018. The large number of caterpillars meant a further increase. of the number of butterflies expected.
Researchers wonder when these ‘disappeared’ caterpillars will reappear and whether they will emerge from the ground as caterpillars or butterflies. “It will be exciting to see how many butterflies will be caught in placed traps in the coming months,” they say.
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