In this article you will learn about the secrets of butterfly survival in winter conditions
Winter is a long period to which butterflies adapt in many different ways. Some of them overwinter as adults, while others undertake long migrations. Some, like Apollo spend the winter in eggs. By learning the characteristics of the Apollo butterfly cycle, you’ll realize that it doesn’t have an easy path to follow until warmer days arrive. If you want to understand our hero’s biology, learn about the longest period of his life, which is Winter. We’ll start with the prelude, which is the formation of eggs.
BEFORE EGGS ARE FORMED
The very short flight period of adult butterflies is the time devoted mainly to pairing and egg-laying. The eggs must be well constructed to provide a safty for the caterpillars in winter conditions. During copulation, the female is protected by a chitinous  material called sfragis.
After a few days, the female starts laying eggs, she is able to lay up to 300 of them. Such a number of eggs increases the chance for larvae to find a host plant , such as some species of Sedum, Sempervivum and Rhodiola.
LIFE FORMATION AND SURVIVAL
Winter and cold are harsh conditions for most butterflies. The time that the caterpillars spend in the eggs is the time that will determine their future population . It is worth considering what happens to the eggs after the female lays them, what processes are responsible for such unusual changes in nature?
The eggs have a chitinous layer that protects future caterpillars from pathogens  and high moisture. They also include various amino acids, proteins and enzymes. The eggs themselves are very solid, but they allow air to flow inside, not all of them come out perfect and not from all of them will hatch caterpillars. There are still many factors to decide. Already in the fourth week after their laying, caterpillars appear in the eggs, but for the next eight months they will lie dormant. The whole cluster will wait until the spring comes during the winter cold.
TIME AND REACTION
While waiting for the time to emerge from the egg, the caterpillar experiences many trials.
The first of them is early spring – a time when temperatures can periodically increase enough to give a false signal to the little ones to wake up. Such a situation can happen even in autumn, when the heat and warm nights last for a long time, and even in winter if there is a sudden warming. It is enough that the temperature rises at night and the morning rays of the sun warm the eggs. For the caterpillars, such a change means death due to the returning cold and lack of food. The large number of eggs produced by each female increases the chances that some will hatch at the right moment. This is one of many adaptations to the conditions in which the butterfly lives.
In the end of Winter and start of Spring comes the proper period of awakening for caterpillars. Depending on the region, it can be slightly shifted in time, but usually it is between March and April. It may also happen that winter will shift and warming will come later. The nights are still chilly in the mountains, but time is pressing as the nutrient material inside the egg is running out. When the time comes, the caterpillars will begin to feed on the egg wall and will chew through its shell. They will then gain strength and take off quickly in search of a host plant.
Adult butterflies equipped with wings are not particularly fast, but their caterpillars are determined to move very quickly. If these little caterpillars don’t find food in time, they won’t survive. This is another adaptation that increases the chances of survival of the species.
A year in the life of a butterfly is trials, chances and races, a series of successes and failures. All this to close the cycle and make the next generation of species. Only in this way they can survive in a harsh and rapidly changing world.
- chitin – a chemical compound (polysacharide) forming the upper skeleton in some organisms along with proteins, calcium and magnesium salts obtained with food in the case of insects.
- host plant – a plant that the organism needs for development in most of its life cycle.
- population – a group of individuals of one species inhabiting a given area at a certain time.
-pathogens – biological agents that cause diseases in living organisms, including viruses, bacteria, protozoa and fungi.
Les Pages Entomogoliques d’Andre Lequet. European Lepidoptera and their ecology: Parnassius apollo
Butterflies in Benelux / Parnassius apollo
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