Cooler weather has been blamed for an increase in caterpillars found in our food - but don't worry, say entomologists, they're edible.

The caterpillars, which develop into moths, are increasingly found in Auckland homes as La Nina's warmer and wetter weather gives way to autumn.

Entomologist and "Bugman" Ruud Kleinpaste said caterpillars - often mistakenly believed to be weevils - moved indoors when the temperature dropped, especially into pantries and grocery supplies. Their proliferation was a matter of perception - "people tend to notice them more in the colder months when they have nothing better to do with their time".

The caterpillars - which develop into moths - destroy grains, flour and dried food products such as nuts and fruit. The most common species are Indian meal moth, warehouse moth, and Mediterranean flower moth.

Their natural function is to recycle dead and fallen waste on the forest floor.

Therefore packaged, dry food was an easy target, said Mr Kleinpaste.

"God invented these characters well before pantries or supermarkets. And humans collect all these foods and store them in convenient bags so bugs find them very easily, all in the one place. Living in a pantry is bliss for them."

Some products are heat-treated.

"The female can lay eggs in the tiniest hole. She's also got better antennae than a spy base and can fly straight to wherever there's food for her babies.

"Others chew straight through any packaging - they've got diamond-tipped mandibles. Once you've got them, you've got them."

Mr Kleinpaste said people could check products for webbing in the bottom of a bag - a telltale sign that caterpillars are inside.

He recommended freezing flour or rice to interrupt the bugs' life cycle, before sifting the caterpillars out.

While they can be unpleasant to find in your food, they are completely harmless if swallowed.

* Freeze bags of flour or rice for 24 hours to kill the caterpillars, then sift them out.

* Store all dry ingredients in airtight containers.

* Place bay leaves in your pantry to deter moths.

* Clean your pantry and cupboards with eucalyptus oil.