butterflies drink nectar
but CATERPILLARS NEED their greens
but CATERPILLARS NEED their greens
CATERPILLARS AND THE
Butterflies in Decline
Many of us have noticed a fall in butterfly numbers over the last few decades. No, it's not our imagination; professional surveys support our suspicions. Butterflies and other invertebrates are being wiped out as their habitats are destroyed, and the specific wildflowers on which they feed and seek shelter are lost.
Butterflies and other invertebrates bring the countryside, a park or garden to life; it is not the same without them.
Why so Steep a Decline?
Figures showing a fall of fifty or eighty percent in the number of different kinds of butterfly over the last few decades are so typical we almost tend to be grateful when it is at the lower end of the range. The situation in Britain is similar to that in most countries in that the main cause of habitat destruction and the consequent loss of wildlife is the relentless intensification of agriculture.
Crop protection involves the direct killing of insects by insecticides, much of it indiscriminate, regardless of whether they are actually the species causing the damage.
But far more harmful is the effect of herbicides targeted at the native vegetation on which butterflies and their caterpillars, and countless other invertebrates, feed. Herbicides, along with soil preparation techniques, uprooting and destruction of hedgerows, draining of marsh land, and the development of aggressive crops which choke out everything else in their path, result in widespread starvation in the insect world and among the birds and mammals that feed on them. A typical field is now a wildlife desert.
There are of course other causes of declining biodiversity as well as insensitive agricultural practices. Road building is one. The duelling of the A90 in Scotland for instance is causing habitat destruction on a massive scale, while increased urbanisation produces housing estates with virtual gardens where soil is replaced by concrete, and flowers by a bunch of brightly coloured cars.
Our aim at CATERPILLAR FOOD PLANTS is to suggest ways in which we can slow down the rate of destruction and bring back the butterflies by growing more of the native wildflowers and leafy vegetation essential for their survival. Adult butterflies drink nectar and or other sugary drinks, but their caterpillars need their greens.
Nectar for Bees and Adult Butterflies
There has been a lot of interest in recent years in the planting of wildflower meadows, and wildflowers in general, to help meet the nectar requirements of adult butterflies and the dual nectar and pollen requirements of bees.
This is excellent, but It's worth remembering that of the thousands of species of insect native to Britain, very few actually drink nectar or eat pollen, just the high profile pollinators - butterflies, moths and bees, hoverflies and a few others.
Bees in fact are extremely unusual insects in that they feed on nectar and pollen both as adults and larvae. Butterflies do not eat pollen, only nectar - and not always even that - and then only as adults. Most insects don't consume nectar or pollen at all.
Caterpillars Need their Greens
ALL herbivorous invertebrates, however, need wildflowers and other native plant life, if not for their nectar and pollen, then for their leaves, buds or roots. If you have ever kept stick insects as pets you will be familiar with the idea of insects eating leaves throughout their lives. Butterflies do so at the caterpillar stage.
The nectar plants in wildflowers mixes are therefore of even more value than we often given them credit for. Conserving and planting more of them is of great benefit over and above the nectar and pollen they provide for the select few.
This is not the whole story, however, as a lot of caterpillar foodplants don't produce meadow-ready pretty flowers, and there are others that for one reason or another rarely appear in wildflower nectar mixes.
Beyond the Nectar
We encourage visitors to our website to look beyond the nectar and to appreciate the needs of butterflies and moths at all stages of their lives. This begins with the laying of eggs by the females, after a careful search to find just the right plant and location, taking into account the needs of her caterpillars for nutrition, camouflage, and defense.
We therefore emphasise the importance of providing not only adult butterflies with nectar but their much more selective caterpillars with the special diet they need. Adult butterflies don't particularly care what flowers they get their nectar from, but they do care what kind of leaves or buds they lay their eggs on. This is because their caterpillars can only eat the leaves of a very small number of different kinds of plant, in some cases they are limited to just one species.
There are various reasons for this. Most plants produce insecticides to protect themselves against insects, and most species of insect have evolved to protect themselves against just a few of these toxins. Secondly caterpillars have evolved camouflage to blend in with the colour and shape of the leaves (or buds) they feed on. If the female butterfly lays her eggs on the wrong kind of leaf, her young will be much more visible to predators. And thirdly, many species have evolved methods of concentrating distasteful substances from the leaves to make themselves unpalatable to birds.
As these foodplants are not necessarily the ones in the popular commercial wildflower mixes that supply the pretty flowers for pollinators we will suggest ones you can add.
There will also be a need for suitable pupation sites and at some stage of the lifecycle, depending on the species, hibernation sites, in crevices in trees and among clumps of vegetation.
A Bio-diverse Green Garden or Block Paving; Which Would You Choose?
Text copyright Trevor Smith April 2019
The images that are not my own are from photographers who generously make their photographs available via Pixabay.com.
Beyond the Nectar to the Needs of the Caterpillar