Scientists say global warming isn't the only threat to humans. Another big threat is the falling numbers of insects. Scientists say half of all insects worldwide have been declining since the 1970s. They warn that over 40 per cent of insect species could die out in our lifetime. The number of insects is decreasing by 2.5 per cent every year. Scientists are calling it an "insect apocalypse". Many species of butterflies, bees and other bugs are now extinct. The scientists say the apocalypse could trigger, "a catastrophic collapse of Earth's ecosystems".
A professor said pesticides used for farming and gardening are killing insects. He said fewer insects mean we cannot feed people. He told reporters: "Three quarters of our crops depend on insects....Crops will begin to fail. We won't have...strawberries. We can't feed 7.5 billion people without insects." A worrying trend is the decline of honeybees. In the USA, the number of honeybee groups dropped from six million in 1947 to 2.5 million in 2014. The professor warned people that: "We can't wait another 25 years before we do anything because it will be too late."