How To Tell What is Eating the Plants in Your Polytunnel

No matter how careful and vigilant you are, the likelihood is that at some point you are going to encounter some form of pest in your polytunnel. But for the novice gardener, it can be difficult to determine what exactly is munching on your plants. Here is a brief beginners guide to identifying some of the most likely culprits:


If you are coming into your polytunnel to find whole plants gone – leaves missing entirely and stems cut off – then the most likely culprits are rabbits, rats or other small mammals. You can deter them with fencing, or collars on plants.

Slugs and Snails:

These slimy creatures will munch their way through the leaves and if their numbers get out of control, can leave a trail of devastation in their wake. The good news is that they do not get away with their pilfering. It is easy to tell where they have been as they leave their slimy trails behind them. Head out at dusk to catch them in the act and pick them off your plants. Encourage birds (or get chickens), place a pond for amphibians and try to encourage natural slug/ snail predators to your garden.


Caterpillars come in a range of different sorts and sizes. They tend to create irregular shaped holes in leaves. Often camouflaged and similar in colour to the leaves they are eating, you will have to look very closely to check for caterpillars, but if you have seen butterflies or moths about then caterpillars are likely to be the culprits. Cutworms will cut through seedling stems at ground level, felling the plants. Pick off caterpillars whenever you see them and deter butterflies from laying eggs on leaves with netting if there is a major problem.


These pests may be tiny but they can do a lot of damage to your plants and crops if left unchecked. Curling leaves can be a giveaway that aphids are doing the dirty work, feeding on the plant juices. Look closely underneath leaves, on stems and especially around growing tips and you will see these tiny creatures at work. Encourage aphid predators such as ladybirds and hoverflies through planting to redress the balance and keep numbers down.

Of course, there are many different creatures that could be sharing in your harvest, not all of them so easily identified. But by ruling out these most common pests, you can get closer to finding a solution for every pest problem.

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