butterflies drink nectar
BUT THEIR CATERPILLARS NEED LEAVES
CATERPILLARS AND THE
Our Butterflies in Decline
Many of us have noticed a fall in butterfly numbers over the last few decades. No, it's not our imagination; detailed 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 or predators of them.
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. 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 block paving, 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.
Wildflower Meadows providing
Nectar and Pollen for Bees and Adult Butterflies
There has been a lot of interest in recent years in the sowing 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 are extremely unusual insects in that they feed both on nectar and on pollen, and that they do so both as adults and as larvae. Butterflies and moths in contrast - with a few tropical exceptions - do not consume pollen at all, and some do not even drink nectar, preferring to refuel on aphid honeydew or rotting fruit. Those butterflies that do drink nectar, do so only as adults. Most insects feed on neither pollen nor nectar at any stage of their lives.
Beyond the Nectar - Caterpillars Need their Greens
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, warmth, 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:
These caterpillar foodplants are not necessarily present in the popular commercial wildflower mixes that supply the flowers for pollinators simply because a lot of such foodplants are wind pollinated and so don't produce meadow-ready pretty flowers, and there are others that for one reason or another rarely appear in wildflower nectar mixes. The good news, however, is that it would be difficult to find a component of a wildflower mix that wasn't a larval food plant for one insect or another. Each is virtually guaranteed to boost biodiversity beyond its own presence.
There will also be a need, to be discussed later, for suitable pupation and 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