From ragweed to tiger mosquitoes, delay and inaction come at a high price – concludes a recent study by Corvinus University of Budapest and HUN-REN. 

The logic of economics and insurance is simple: prevention costs far less than late intervention. In Hungary, more than 200 invasive plant and animal species are officially registered. The damage they cause is not only an environmental concern but also an economic one. When a non-native species settles here, we tend to think of it as an ecological issue. In reality, the bill is paid by the economy. Invasive species reduce crop yields, damage infrastructure, increase healthcare costs, and hurt tourism – and the losses eventually show up in the national budget and household expenses. 

Milder winters and longer growing seasons are creating more favourable conditions for their spread. Floods and storms also help them disperse, while global trade and tourism keep opening new routes for their introduction. 

The real question, therefore, is not whether to spend on combating invasive species, but when. The economic logic is clear: prevention is always cheaper than delayed and much more expensive intervention – emphasise Imre Fertő, Professor at the Institute of Sustainable Development at Corvinus University and Director General of the ELKH Centre for Economic and Regional Studies, and László Zsolt Garamszegi, Research Professor at the HUN-REN Centre for Ecological Research, in their study published in the Hungarian Economic Review. 

Many local governments and authorities assume that if things go wrong, help will come “from above”. This mindset – known as the “soft budget constraint” – means that small, predictable costs are avoided today, only to face massive, exponentially higher expenses later. It’s the classic conflict between short-term gains and long-term losses. 

Japanese knotweed, for example, was introduced to Europe as an ornamental plant and seemed harmless for decades. Today, it cracks building foundations, spreads along roadsides, and costs billions to eradicate. The same pattern applies to species like milkweed, tree of heaven, black locust, ragweed, or nutria: failing to finance early control efforts leads to paying many times more for emergency interventions later, because their spread is not linear. In short, delay and indifference are systemically expensive. 

Hidden Costs Are Real 

Prevention is often seen as costly, while the damage seems uncertain. But this is exactly how insurance works: it’s worth paying a smaller, certain cost now to avoid a large, probable loss later. International experience shows that early measures against invasive species pay off several times over. 

Direct costs – such as crop loss or pesticide expenses – are relatively easy to measure. But much of the real loss lies in the “invisible” costs: declining water quality, disappearing species, and reduced recreational value. These don’t appear in the state budget but steadily erode social well-being. Climate change, globalisation, tourism, and urbanisation are all increasing exposure, while defence systems often remain slow and fragmented. 

What Can Be Done? 

The key to an effective response lies in speed and accountability – supported by dedicated funding, clear thresholds, and priority lists. Early warning systems, reporting mechanisms, well-funded rapid response, clear responsibilities, and unified data collection all strengthen fiscal discipline and encourage prevention. 

It’s worth investing in predictive models, making hidden costs visible to society, and building real cooperation both internationally and across sectors within Hungary – from nature conservation to public health, from infrastructure management to agricultural policy. 

“We can’t bury our heads in the sand – we must act now. The arrival of invasive species is inevitable, and the bill will come due either way. The only question is whether we pay less now or much more later. Preventing biological invasions is not only an ecological duty but a sound economic choice. Recognising this saves both time and money: early action can slow the spread of harmful species and mitigate their impact,” says Imre Fertő, lead author of the study. 

In Hungary, based on current data and methods, the future costs linked to invasive species are estimated at around 93 billion forints. Globally, more than 3,500 invasive species have been identified, and the annual damage caused by biological invasions is roughly 156 trillion forints – nearly three to four times the size of Hungary’s annual budget. What’s more, these costs are at least quadrupling every decade.