Red admiral butterfly

Butterflies and caterpillars

cabbage white eggs
Cabbage white eggs. Image: Martin Mulchinock

There are a few things to understand about caterpillars. Just like the ugly ducking, these voracious, plant-munching maggots will one day metamorphose into a beautiful butterfly. What’s more important to understand is that most caterpillars have a particular host plant that they feed on This means that the adult females will seek out the correct plant type and lay her eggs on the leaves so that the emerging larvae (caterpillars) have a good food source to eat.

So the cabbage white butterfly will lay her eggs on the underside of nasturtiums and brassicas. You can actually lure the adult female away from your precious cabbages by planting clumps of the closely related nasturtiums nearby.

Caterpillars are an important level in the food chain. Many birds feed their young beak-fulls of wriggling caterpillars as they mature. Wasps and other predatory insects snatch young caterpillars to feed to their developing larva. If you remove caterpillars from the food chain it could have far reaching effects on the local wildlife.

Caterpillars of the peacock butterfly. Image: Martin Mulchinock.

Remember that some caterpillars are the larval stage of our garden beauties. These black fluffy caterpillars have a sparkly glittery effect and can be found around June and July on stinging nettles. If we all killed or pulled out the stinging nettles in our gardens these caterpillars would starve. And yet when they hatch from their chrysalis they turn into one of the most beautiful butterflies we know, the peacock butterfly. This little cluster of caterpillars are doing no harm and are in fact eating the nettles for their supper. Imagine the knock on effect of spraying them. The garden would be devoid of their fairy like activity. Plants would not be pollinated and the birds that eat them would starve. Remember, butterflies are another pollinator in trouble and we need to do everything we can to support them.

Comma Butterfly
Comma butterfly. Image: Martin Mulchinock

How to help butterflies

  • It’s time to learn more about these elegant creatures. Buy an identification book that includes the caterpillars and the adults or join an online forum. Study the bugs in your garden and start to appreciate their delicate existence and lives. Find out what the caterpillars are and what they will grow into and engage the children so that they learn to appreciate nature too.
  • If the caterpillars are a nuisance species then try to find a way to live with them. Grow a patch of their host plants somewhere or find another patch of their host plants in some wasteland or woodland and move them there, very carefully. Make sure that you identify the caterpillars and the host plant first.
  • Remember that all sorts of other garden wildlife will feed on caterpillars and bugs. If they are a nuisance species then knock them off for ground feeding birds, gently wash them off with the hose, pick them off and move them to wilder area. But if they aren’t leave them to mature into butterflies to fill your garden with colour and movement.
  • Look at their lifecycle and the timing. Can you grow your plants so that they don’t coincide with the caterpillar stage?
  • Cover your plants with mesh or fine netting while the adult butterflies are looking for host plants but make sure that the netting is held above the plants and not touching so that the butterflies can’t lay their eggs through the net.
  • Learn to identify the eggs of nuisance caterpillars. Cabbage white butterflies, which can cause no end of damage, lay their eggs underneath the leaves of cabbages either singly or in clusters of around 50-80. The eggs are torpedo shaped and a pale orange/yellow in colour. Look at them under a magnifying glass and compare them to your identification table. If they are the dreaded cabbage white eggs, then you could pick them off, but if you are brave and don’t use pesticides in the garden, nature may well take over and feed off the resulting caterpillars.
  • Try to live and let live if you can. Garden insecticides are designed to kill insects. They don’t discriminate and don’t know the difference between good bugs (bees, butterflies and ladybirds) and what you perceive to be pests.

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