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How to improve your space for nature: worms, caterpillars and pesticides

Updated: May 31, 2019

Caterpillars of the small tortoiseshell photo by Jeff de Longe Vantoux from Wikipedia

Worms and caterpillars

In the whole circle of life, worms and caterpillars are incredibly important. They form an essential source of food for birds and mammals. Even seed eating birds eat worms and caterpillars on occasion and all baby birds need the high protein content of these creatures to give them a good start in life. Birds in cities tend to have smaller families and one of the reasons for this may be that there aren’t enough worms and caterpillars to be foraged from our parks and gardens. So, whatever you do, make sure you leave worms and caterpillars for the birds. The ones who survive will often turn into lovely butterflies and moths, so they are worth waiting around for too. Along with caterpillars are a whole range of beetles and other bugs, wherever possible leave them alone to thrive

Caterpillars are often specialist feeders. They need specific plants to graze on so that they can mature. If you’ve hung around any wildlife garden or nature park you’ll be aware that nettles are a great source of food for a wide variety of caterpillars. Most of our worm species have evolved to live off our common weeds, so if you see a worm on a weed, chances are that’s it’s specialist plant, and it would die if you moved it across to something else. Instead, cultivate / encourage any weeds that appear particularly tasty to the worms you come across in your garden.


Don’t use them. Pesticides tend to kill everything, not just the animals you’re trying to get rid of. The poison can also enter the food chain. If you’re trying to poison caterpillars, they might be picked off by a bird who feeds these dying worms to their young who then get poisoned. The dying fledgelings might then get eaten by a bird of prey or scavenger. There are surprisingly high levels of poisons found in the blood of many predators due to the wide use of poisons in our towns and cities.

Poison to be very scatter gun and can easily pass from the animals you wanted to kill to animals you don’t want to kill. Slug pellets for example definitely kill off slugs but can also harm the hedgehogs that come along and snaffle up the slugs.

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