Bugs are declining around the world, but there's no budget to investigate the issue in New Zealand.

Around the world, insect species are disappearing at a frightening pace which could be disastrous for entire ecosystems.

There is no hard data on insect numbers in New Zealand, but anecdotally, entomologists are afraid New Zealand isn't faring any better.

Insects are a vital part of the natural ecosystem and in New Zealand there is a secondary concern, conservation, but funding on research is not forthcoming.

A study of west Germany's nature reserves found a more than 75 per cent decline of insect numbers over 27 years and around the world insects are disappearing faster than entomologists can record them.

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SUPPLIED Canterbury Museum curator of natural history and the past-president of the Entomological Society of NZ Cor Vink said insects are vital for the environment.

There are about 12,500 described insects in New Zealand and more than 4000 don't have names. At least 70 per cent, you won't find anywhere else and for some insect groups, it's 95 per cent.

Canterbury Museum curator of natural history and the past-president of the Entomological Society of NZ Cor Vink said people had certainly noticed the 'windshield effect'.

The windshield effect was the mess made by insects on a cars windscreen after a long drive, or now, the lack of mess.

"Fewer insects means you have less food for birds, some plants might not be as well controlled and there are fewer pollinators around," Vink said.

"They're really vital for the environment.

"If all the mammals on Earth disappeared, there wouldn't be much effect, but if all insects disappeared ..."

​Vink said agricultural sprays, spray drift into natural habitats and habitat loss all had an effect on insect populations.

"Some insect conservation is working well, some is struggling," he said.

"Endemic pest species like the New Zealand grass grub have taken a dive due to DDT.

"Once DDT hit them, their numbers massively declined."

GRANT MATTHEW/STUFF There are about 12,500 described insects in New Zealand and more than 4000 that don't have names. At least 70 per cent, you won't find anywhere else.

DDT was a highly toxic insecticide used extensively in the 1950s and 1960s and was eventually banned in New Zealand in 1984.

Vink said climate change may also have an effect on insect populations.

"An obvious example would be alpine areas," he said. "Things that are just above the tree line have nowhere to go.

"If there was funding available I'm sure you could find the people to do the research," he said.

JASON OXENHAM/STUFF Libby Burgess said the main issue was habitat destruction and recommended planting native gardens as a resource for birds and insects.

Victoria University professor of entomology Phil Lester said the windscreen was a "bit of a litmus test", however, to his knowledge, there was no data on the number of insects.

"Growing up leaving a window open over night your house would be full of moths and other insects," Lester said.

"Most of New Zealand would have an opinion on it, but I don't see a lot of industry worrying about it.

"Entomologists are probably concerned, but it isn't affecting the industry."

123rf Fewer insects means you have less food for birds, some plants might not be as well controlled and there are fewer pollinators around, Vink says.

Lester said he suspected the decline in insect numbers had been a "long and gradual" thing.

"Because it's been slow, people aren't as upset as they might be," he said.

"We should be conducting experiments.

"I think it's really important to get a handle on what has changed and why it's changing."

SUPPLIED Victoria University professor of entomology Phil Lester says he thinks it's really important to get a handle on what has changed and why it's changing.

Plant and Food Research science group leader of the applied entomology group Libby Burgess said the main issue was habitat destruction.

"Wherever people put buildings and roads and remove forests,wetlands and other native habitats there will be less insects," Burgess said.

She said there was a link between New Zealand's native birds and insects.

"For example, Tuis ingest insects for protein to be strong enough for breeding and to feed their chicks," she said.

"People should be thinking about planting native gardens as a resource for native birds and insects."