If you’ve noticed a few less bugs buzzing about, that’s something to be concerned about, scientists warn. The number of insects in the world appears to be on the decline. Alongside this reduction in the world’s bugs, there has never been much real long-term awareness of the decline.

But, warning signs have been around for years about plummeting insect populations worldwide, scientists say. The declining numbers are so much so now that the levels are seen as potentially "catastrophic" and have not been well-understood until now.

More than 40 percent of insect species are dwindling globally and a third of species are endangered, a new peer-reviewed study shows. Researchers recently released the results of an analysis of more than 73 historical reports on insect population declines. Apparently, the "total mass" of insects has fallen by 2.5 percent each year. "If the decline continues at this rate, insects could be wiped off the face of the Earth within a century," they said.

The first global scientific review of insect population decline was published in the journal Biological Conservation and the findings are "shocking," its authors said.

"In 10 years you will have a quarter less, in 50 years only half left and in 100 years you will have none," study co-author Francisco Sánchez-Bayo, an environmental biologist at the University of Sydney, Australia, told The Guardian. "If insect species losses cannot be halted, this will have catastrophic consequences for both the planet’s ecosystems and for the survival of mankind," Sánchez-Bayo added.

In other words, this is a very big deal for all of us.

According to The Washington Post in 2014, biologists estimated that in the past 35 years the abundance of invertebrates — including beetles and bees — decreased by 45 percent. Likewise, in Europe, insect numbers are dropping dramatically. For example, another study showed a 76 percent decrease in flying insects in German nature preserves.

Now, according to Proceedings of the National Academy of Sciences, this startling loss of insect abundance extends to the Americas.

All of this might lead to what scientists are calling a "catastrophic collapse of nature’s ecosystems."

But according to the new review, the proportion of insects in decline is currently twice as high as that of vertebrates and the insect extinction rate is eight times faster than that of mammals, birds and reptiles. Insects are a food source for many animals, are critical pollinators and recycle nutrients back into the soil.

Habitat loss because of "intensive agriculture is the top driver of insect population declines." The heavy use of pesticides and invasive species were also pinpointed as significant causes to the declines of insect populations.

"Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades," the review’s co-authors wrote. "The repercussions this will have for the planet’s ecosystems are catastrophic, to say the least."