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How to grow a cress caterpillar

A fun food-based activity to keep kids entertained at home.

Create a colourful caterpillar, watch cress grow and eat the tasty results.

Follow our simple instructions to transform eggshells and cress seeds into a caterpillar.

There are hundreds of types of caterpillar in the UK to choose from. We've highlighted a selection of interesting ones for inspiration.

How long does cress take to grow?

Cress grows quickly. You should start to see your seeds sprouting within a few days and often in as little as 24 hours. After seven days, the cress will usually have grown at least three centimetres tall and be ready to harvest.

You will need:

  • eggshells, clean and dry
  • cress seeds - sometimes called salad or garden cress (Lepidium sativum)
  • craft supplies, such as non-toxic poster paint
  • water
  • cotton wool
  • salt dough or play dough

What to do

  1. Pick which caterpillar you want to make. Check out the photos below for ideas.
  2. Decorate the eggshells to match your chosen caterpillar's colours and patterns. Leave them to dry.
  3. Roll some little balls of salt dough to make caterpillar legs. Attach four to the bottom of each eggshell.
  4. Submerge some cotton wool in water and place a piece inside every eggshell.
  5. Sprinkle a teaspoon of cress seeds onto each one.
  6. Place your caterpillar in a warm, sunny spot.
  7. Check it daily. If the cotton wool looks dry, add some water. After a few days the seeds will start to sprout. Your cress should be ready to harvest in about a week.
  8. Harvest and wash your cress. Use it to make a tasty salad or sandwich.

Caterpillar inspiration

Caterpillars are the second stage in the lives of butterflies and moths.

There are 59 different types of butterfly in the UK and just under 2,500 types of moth.

Here's a selection of colourful British caterpillars with dramatic patterns to use as inspiration for decorating your eggshells:

Colourful caterpillars

Many caterpillars are dull browns and greens, which helps them stay hidden on leaves and branches.

Others have gone for the opposite approach and are decorated with vivid colours and patterns. This is to warn predators such as birds that they taste bad or are dangerous to eat, or to at least fool the predators into believing this.

Some caterpillars even develop disguises that, combined with particular behaviour, startle predators. For example, the eyespots of the elephant hawkmoth caterpillar are thought to make it look like a more intimidating animal.

How many legs does a caterpillar have?

Like other insects, caterpillars have six proper legs. They are attached to the part of their body nearest their head. Caterpillars have additional stumpy body parts called prolegs towards the back of their body that help them move around. They use them to grip onto twigs, stems and other surfaces.

Different caterpillar species have different numbers of prolegs - between two and five pairs. So, caterpillars can look like they have up to 16 legs, although only six are true legs with joints like our knees and ankles.

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