Hemiptera

Hemiptera is a massive order of insects commonly known as "true bugs."

This group is incredibly diverse, containing more than 80,000 species.

These insects include well-known creatures like cicadas, aphids, and leafhoppers. They also include predators like assassin bugs and parasites like bed bugs. Most hemipterans live on land, but some have adapted to freshwater environments. Examples of aquatic species include water boatmen, backswimmers, and giant water bugs.

The name Hemiptera comes from the Greek words for "half" and "wing." This refers to the forewings of many species, which are hardened at the base but membranous at the tips.

The most distinctive feature of this order is their specialized mouthparts.

They possess a rostrum, which is a beak-like structure. Inside this rostrum is a piercing-sucking tool called a stylet. This stylet is formed by modified mandibles and maxillae. The stylet contains two separate channels. One channel carries saliva outward into the food source. The other channel pulls liquid food inward. To move these fluids, the insect uses two different pumps. A salivary pump pushes saliva out, while a cibarial pump extracts the liquid.

Both pumps are powered by large muscles located in the head.

Hemipterans use these mouthparts to feed in several different ways. Most species are herbivores that drink plant sap. To help with this, they inject enzymes to begin digestion outside of their bodies. They use amylase to break down starch and polygalacturonase to weaken plant cell walls. They also use proteinases to break down proteins. However, not all true bugs eat plants. Some, such as assassin bugs, are predators that hunt other insects or small invertebrates. Other species are hematophagous, meaning they feed on blood.

Scientists divide the order Hemiptera into four distinct suborders. The first is Heteroptera, which contains more than 45,000 species. These are often larger bugs, such as shield bugs or assassin bugs. The second is Auchenorrhyncha, which includes over 42,000 species like cicadas and leafhoppers. Many in this group can jump or make loud calls. The third is Sternorrhyncha, which contains about 12,500 species like aphids and whiteflies. These are often small and stay in one place. Finally, there is Coleorrhyncha, a small group of fewer than 30 species known as moss bugs.

These are rarely seen and live in moss.

The history of Hemiptera stretches back hundreds of millions of years. The fossil record shows they have existed since the Carboniferous period.

Some of the oldest fossils belong to the Archescytinidae from the Lower Permian. Different groups appeared at various times in Earth's history. For instance, the Heteroptera first appeared during the Triassic period. Aphids and scale insects also appeared during the Triassic. The Coleorrhyncha have a long history as well, dating back to the Lower Jurassic.

These insects have a unique way of growing called hemimetabolous development.

This means they do not undergo a complete metamorphosis with a pupal stage. Instead, they hatch as nymphs that look similar to the adults. As the nymphs grow, they undergo several molts. During these stages, wing buds begin to develop. The final stage involves the development of functional wings and sexual organs. Some aphids even use parthenogenesis to reproduce. This allows females to produce unfertilized eggs that create clones of themselves. This ability helps them reproduce extremely rapidly when conditions are good.

Humans have a long and complex relationship with Hemiptera. Some species are major agricultural pests because they damage crops by sucking sap. Others act as vectors for serious diseases. For example, kissing bugs can transmit Chagas disease.

On the other hand, some species are useful to humans. Certain bugs are used for biological control of invasive plants or pests. Others are cultivated to extract substances like shellac or dyestuffs, such as cochineal.

Even cicadas have been used as food and appear in ancient literature like the Iliad.