Caterpillars are insect larvae that belong to the order Lepidoptera. These small creatures are very vulnerable and can easily become someone’s prey, so they have to defend themselves in order to turn into one of the most beautiful insects after some time.
Structure
Most of them have cylindrical bodies, consisting of several segments, with three pairs of real legs on the chest and several pairs of short and thicker false limbs on the abdomen. On the head are six pairs of small eyes (stem) that function when light is detected, but not when forming an image. They have short segmented antennae and strong jaws. Many caterpillars in the Lepidoptera order are called worms, for example, the silkworm (silkworm) and the army worm (Spodoptera frugipeda).
What do they eat
Caterpillars are known for their insatiable appetite. Usually they feed on the leaves of various plants, although some can eat insects or other small animals. Leaf-eating species can cause significant damage to fruit trees, crops, ornamental plants, deciduous trees, and shrubs. For example, caterpillars of the cabbage moth (Trichoplusia ni) can eat up to three times their body weight daily. In addition to the damage that these caterpillars inflict by eating cabbage leaves and related crops, the feces they produce, known as frasses, can stain leaves and make plants unsuitable for sale. Examples of insect-eating caterpillars are Feniseca tarquinius, which prey on woolly aphids, and the butterfly Alesa amesis, which feeds on the nymphs of the insects of the order Homoptera.
Features of individual species
Some caterpillars have special respiratory structures that allow them to survive in aquatic habitats. For example, the larvae of some pyralid mollusks (family Pyralidae) are aquatic, and several representatives of the genus Hyposmocoma (family Cosmopterigidae) have an amphibian caterpillar stage. Some caterpillars weave silk covers that provide protective cover. They often interweave leaves, pebbles and much more, so they look like part of their natural surroundings.
Defense strategy
All types of butterflies and moths begin life with a caterpillar. This is a very vulnerable form of the insect, therefore, needs protection.
Their appearance varies greatly, especially the color, which plays a major role in the ability to protect themselves from predators. In many cases, their color should imitate the appearance of the environment, and it changes as it grows. For example, young larvae of many Papilio butterfly butterflies are white and brown in color, they resemble bird droppings on leaves, but over time their appearance changes in such a way that the colors eventually become camouflage, allowing them to merge with leaves and plant stems. In some caterpillars, the color is noticeable or enhanced by the presence of such signs as false organs of vision, which can deceive or scare predators.
Other protection strategies used by caterpillars include the release of foul-smelling substances, the use of sounds, the generation of vibrational signals and sequestration of chemicals toxic to predators in the tissues. The caterpillars of the large nocturnal peacock eye (Saturnia pyri) send ultrasonic warning signals to deter predators. The butterfly caterpillar caterpillar (Drepana arcuata) produces vibrational signals to protect its territory from intruders of the same species; she bangs her jaws on the surface of the sheet and scratches it with her feet, covered with hairs.
Larvae of monarch butterflies (Danaus plexippus) rely on a protection system associated with their unique ability to feed on milkweed plants (Asclepias). These plants produce compounds known as cardenolides, which are usually toxic to animals. The larvae of the monarch butterfly are not affected by the poison, and they are able to isolate the compound in their tissues. Since the poison remains in insects at subsequent stages of development, they are toxic to vertebrate predators both in the form of larvae and in the form of adult butterflies.
Classification
There are various types of tracks. This is primarily due to the diversity of the lepidoptera themselves. Interestingly, the color of the larva does not always correspond to the coloring of the adult. One of the classifications by which species of caterpillars are determined is based on what they eat.
- The group of polyphages is represented by their representatives who are completely illegible in food, who can eat any plants. These include night butterflies, for example, wine hawthorn, ocular hawthorn, blind hawthorn, Kaya bear, moths, peacock-eye and others.
- The group of monophages includes feeding on only one specific species of caterpillar plants. These are cabbage, apple moth, silkworm and some others.
- The group of oligophages includes those who feed on a certain type of plant; they represent one family or type. These include: swallowtail, pine scoop, polyxena and others.
- Xylophages are caterpillars whose food is wood or bark. This group is represented by leafworms, woodworms and others.
Different stages of the life cycle
The caterpillar is the second phase of the butterfly's life cycle. Other phases: egg (first phase), pupa (third phase) and butterfly (fourth / last phase). The time required to complete the life cycle of a butterfly can take from one month to a calendar year.
Egg phase
She is the first in the life cycle of a caterpillar. Eggs can be of different shapes, they can be round, cylindrical, oval, etc. Eggs are usually laid on the leaves of plants. Females can also leave eggs on their stems. Their location on the leaves facilitates the extraction of food at the next stage of development (caterpillars). The eggs are protected by a hard outer coating known as chorion. The thin layer of wax that covers it helps prevent eggs from drying out. This phase usually lasts several weeks. However, eggs that were laid in the winter months are at rest during the cold season. Larvae hatch from them only with the onset of the spring season.
Second stage of development
Caterpillars are very insatiable creatures. They go through various phases of growth during their development. Apolysis is a process in which a caterpillar drops a cuticle, an outer layer of protein and chitin. By the time the last phase of growth is reached, the development of the wings begins.
Caterpillar legs are of two types, that is, real and false. If the first is only three pairs, then the second on the body can be six
The second and third thoracic segments of the body of the caterpillar have wing discs. Their development is associated with trachea. They grow rapidly in the last phase of this phase. Hemolymph gradually displaces the wings through the epidermis.
Pupa phase
This is an intermediate stage between the larva and the adult butterfly. When the caterpillars turn into pupae, they stop feeding and look for a substrate for the last molt. As you approach the pupal stage, a hormone of metamorphosis is produced, which provides a change in the phases of development. Wings undergo rapid mitosis, so many nutrients are required at this stage. To protect themselves from predators, pupae make certain types of sounds.
Adult
A fully developed caterpillar form is known as an adult. Butterfly wings appearing at the pupal stage take some time to dry; this process takes about 3-4 hours. For the imago to fly correctly, the wings must be deployed.
Why do caterpillars grow so fast
An important part of a survival strategy is rapid growth, because at this stage of its life cycle many species are extremely vulnerable to predators, so short pupation periods give them the best chance of survival. Nevertheless, there are species that remain caterpillars for a long period of time, some winter, and sometimes remain in the tree trunk for several years.
