Ladybirds & Lettuce

Updated: 02/03/2009

Source: Vegetables Victoria Editorial – 2 March 2009

Ladybird beetles are very common in lettuce crops over summer and you may even find a few on lettuce in your garden or local fruit & veg shop.

If you buy unbagged / loose lettuce, just rinse in cold water to remove any traces of soil or insects.

Vegetable crops attract hundreds of different insects, from beetles and caterpillars to bees and moths.

Only a few of these insects are crop pests and many of the pests are only a problem for a short time.

Most insects are “Good Bugs”: predators, pollinators and parasites of crop pests.

“Good Bugs” include ladybird beetles, hoverflies, midges, lacewings, earwigs, wasps and mites.

Ladybird beetle 2

The most visible predator is the ladybird beetle which feeds on aphids, fruit flies, thrips and other plant pests that damage our food crops.

A single ladybird can consume
5000+ aphids in 3-6 weeks.

Ladybird beetles are a good indicator of a healthy and sustainable vegetable production system.

Ladybirds lay hundreds of eggs in colonies of aphids and other plant pests.

On hatching, they immediately begin to feed and can consume 5000+ aphids in 3 to 6 weeks.

Pest management practices such as IPM recognise the value of ‘Good Bugs’ as our first line of defence against crop pests.

But despite the great success of IPM, growers must keep applying insecticides while supermarkets and their customers refuse to accept the occasional bug in their lettuce.

Most insecticides including ‘organic pesticides’ such as Pyrethrum and Rotenone (Derris dust), kill the “Good Bugs” as well as the pests.

“It comes back to the specifications that growers must meet to supply vegetables”, says prominent vegetable spokesman Richard Bovill.

“Supermarkets must satisfy the expectations of their customers who generally have a zero tolerance for ANY bugs on vegetables.”

ladybird beetle 1

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