Ladybird, Ladybird, Fly Away From My Cucumbers

A couple of years ago a friend asked me to identify some mysterious yellow caterpillar-type creatures that were eating her cucumber leaves. Though I had never encountered them before, it did not take long to find out that they were the larvae of the 26-spotted ladybird.

It was apparently a very good year for this pest. After I had identified it for my friend, I discovered it in my own garden, then a number of other vegie growers in the area mentioned that it was in their gardens. I decided to break the pest ladybird's life cycle by squashing every one I saw and pulling up the cucumbers, their favourite snack (in my garden at least). I did wear my specs to make sure I was correctly identifying and only destroying the pest species and not any beneficial ladybirds.

Last year, I did not see any. This year, there were a few early in the season, which I quickly squashed. However, in the last week they have returned in large numbers. The giveaway sign is skeletonised leaves on cucumbers, canteloupes, pumpkins, zucchinis and potatoes. They might also feed on beans and tomatoes so be watchful for leaf skeletonising on all crops. Look on the backs of the leaves and you will see the grubs munching away, usually they are yellow, but sometimes can be a brownish ochre colour. There could also be clusters of yellowish eggs. The adult beetles feed on leaves too, but they are usually found on the tops of the leaves.

Pyrethrum sprayed directly onto the grubs will kill them. However, all I have done is squash any adults and larvae I've found and brush eggs off the leaves. At this stage of the season, in this area, the cucumbers and other curcubits have passed their best and are usually ready to come out of the ground; yesterday I pulled most of them out. The one zucchini that is still producing well was checked all over and had damaged leaves and pest inhabitants removed.

You can drop the pests into a jar with a little methylated spirits in the bottom if you are averse to squashing.

Most ladybirds are friends in the garden. Some eat small pests such as aphids, mealybugs and spider mites, others browse on powdery mildew that might be on plant leaves. Do not make the mistake of thinking that all ladybirds are benign or beneficial. If you are in any doubt, catch one and count the spots, then get rid of the pest species before they get rid of your crops. The 28-spotted ladybird is a different species from the 26-spotted, but is also a garden pest.

This website is a useful guide to ladybird identification: http://www.brisbaneinsects.com/brisbane_ladybirds/LadybirdFieldGuide.html