Photo by IRRI ImagesThere are supposed to be at least seven species of ladybird on Tenerife, and according to David and Zoë Bramwell’s excellent book, Historia Natural de las Islas Canarias, one of these is very common. I have been on Tenerife for nearly three years and in all that time I have only ever seen one of these pretty little beetles, so where have all the Canary Islands ladybirds gone?
Where have all the gardeners’ friends gone?
Now I’ll be the first to admit that I haven’t gone out specifically looking for ladybirds, but I do keep my eye out for interesting wildlife and this little insect is conspicuous by its absence. Not so the aphids and other pests that ladybirds eat though – plants all over the island are so often very badly infested.
The problem I think is caused by the very widespread use of insecticides by gardeners and farmers here. These poisonous substances kill the pests they are intended for, but they also kill the “beneficial insects” like ladybirds as well.
And not only other insects such as ladybirds get killed but birds and reptiles can, in turn, become victims of the poison if they inadvertently eat dead or dying insects that have succumbed to a pesticide. If a lizard or small bird dies from eating poisoned insects it can then become the food of a hawk or a crow and kill them as well. I am certain there would be many more birds on Tenerife if the use of insecticides were cut down.
Singer-songwriter Joni Mitchell had a big hit with her song Big Yellow Taxi, in which she sings: “Hey farmer, farmer, put away your DDT now,” and warns of the threat to wildlife and the ecosystem.
Big yellow taxi – Joni Mitchell in concert 1970
It’s not that I don’t sympathise with people who are desperately trying to save their prized plants, and in the case of farmers, their crops, which they depend on for income, because I do understand how they feel. I have had battles against insect pests that have been destroying plants I have had growing as well.
The problem is that the wonderful climate of Tenerife doesn’t just suit us, it suits the insect pests too and in the warm conditions they breed and breed and breed.
Whitefly, mealy bugs and woolly aphids cause terrible problems all over the island and sometimes in heavy infestations the latter of these insects can cover the leaves, stems and branches with white fluffy material they exude.
Red spider mites are difficult to see and to eradicate, and scale insects with their armour-plated backs are another common pest. The mealy bug not only crawls from one plant to the next but it can also be hiding in the ground on the roots.
But there is an answer and it doesn’t mean that we have to endanger other forms of life – there are natural predators that eat insect pests. The ladybird is one of these but there are many more, and there are plenty of companies who supply specific biological controls.
Search on the Internet for “biological pest control” and you will see what I mean. There are loads of businesses selling ladybirds, lacewings, red spider mite predators, mealy bug killers and many more including nematode worms that kill slugs and snails.
The parasitic wasp species Encarsia formosa is apparently a very efficient way to control whitefly, so why haven’t we got some on Tenerife? Obviously with the plentiful food supply, any predator species would love it here and would reproduce, just like the pests it preys upon.
And insect predators do work well once you have got them. I have had yellow-bodied and black-legged Oleander Aphids (Aphis nerii) on my Scarlet Milkweed (Asclepias curassavica) and another smaller type of greenfly all over my Red Viper’s Bugloss or Tajinaste Rojo (Echium wildpretii), and in both cases the larvae of the Hoverfly (Spaerophoria scripta) eliminated the pests.
The Hoverfly, named after their amazing ability to hover in flight, is a thin-bodied insect banded with stripes somewhat like a wasp. Adult Hoverflies feed on nectar so flowers in your garden or on your balcony will help attract them.
Its larva is a small green legless grub that clambers about over leaves and stalks hunting down the aphids and other tiny insect pests. I am sure many gardeners not knowing what the Hoverfly larvae are think they are some type of caterpillar and kill them, when, in fact, they are the gardener’s friends.
That is what we want – many more of the insects that help us in our battle against the pests. Most of the companies selling biological controls are in the US or UK and cannot deliver to Spain or the Canary Islands so what we need is a business that can. If anyone wants to set one up I am sure you’d have no shortage of customers!
Footnote: Originally published in the Tenerife Sun.
Copyright © 2013 Steve Andrews. All Rights Reserved.