Insects make up a huge percentage of the Earth’s biodiversity and are an irreplaceable link in the food chain. Many larger mammals depend almost entirely on the existence of both diurnal and nocturnal insects as not only a vital source of food but also as the pollinators of plants that are vital as the diet and habitat of so many creatures that rely on them for survival. Insects can be divided into two main groups – those that are positively phototaxic (attracted to light, such as most species of moth), and those that are negatively phototaxic (insects that are repelled by light).
Moths, also known as ‘Heterocera’, are related to butterflies and both these species belong to the Lepidoptera order, though moths are far more common, with there being nearly 10 times the number of moth species than butterfly species. The main difference between the two is that butterflies are strictly diurnal (active during the day), whereas the vast majority of moths are crepuscular (active at dawn/dusk), or nocturnal.
Many moth species are considered agricultural pests as their larvae feed off crops, and some species belonging to the Tineidae family are thought of as household pests, due to the fact that their larvae feed on clothing, blankets and other items around the home that are made of proteinaceous fibers such as silk or wool. Moths are preyed upon by nocturnal insectivores such as bats, owls, lizards and frogs and these species numbers’ would decline rapidly without the existence of the humble moth, as would many varieties of plant, which depend solely on moths for pollination.
Fireflies, also known as ‘lightning bugs’ are so-called because they use bio-luminescence to attract prey and mates. This light is chemically produced in the lower abdomen, and can be yellow, green or orange/red in color. Fireflies are winged beetles that belong to the Lampyridae family and the Coleoptera order. There are around 2000 different species of firefly, with potentially many more to be discovered. In some species the females cannot fly and are wingless. Fireflies are carnivorous and prey on snails, other small insects and beetle/insect larvae. They are mainly found in the tropical and temperate climates of marshes and wooded areas. They are small, soft-bodied beetles that are usually light-dark brown in color.
Earwigs are a species of arthropod and are found across the globe, with there being approximately 2000 known species, which are split into 12 separate families and make up the insect order ‘Dermaptera’. They are found in moist, dark crevices such as in rock walls and under rotting tree bark, where they hide during the day; and at night they can be observed feeding on other insects and some varieties of plant. Earwigs are typically between seven and 50 millimeters in length, are brown or black in color with elongated bodies and cerci, which are paired appendages on the rear segments of many arthropods, and can be used as weapons and also as an aid during copulation. The name ‘earwig’ is derived from Greek and means “skin wings” which refers to the leathery wings that the earwig possesses, though very few species actually use them, and many will spend their entire lives on the ground. The name may also have been derived from the old wives tale that earwigs crawled into people’s ears at night and laid their eggs in human brains. Obviously, this is a myth and though there have been incidents where earwigs have accidentally crawled into human ears, there has never been any harm done by the earwig.
There are over 2,500 mosquito species, which belong to the Culicidae family, and the Diptera order. They are particularly unpopular insects among humans because they feed on the blood of living mammals (including humans), and can spread diseases that are very harmful such as yellow fever, malaria and filariasis.
Mosquitoes are a type of fly, and like all flies, have four stages in their short life-cycles: beginning as an egg, hatching into larva, becoming pupa and finally, imago (adult). Adult female mosquitoes usually lay their eggs in or near stagnant water, where the offspring will remain until they reach maturity. Their development usually takes about 40 days, but this depends on temperature, species and climate.
Crickets belong to the Gryllidae family and are a small insect that is generally either black or brown in color, with long antennae and a slightly flattened body. Crickets are omnivores and while they will usually feed on plants and fungi, they have been known to prey on other weak or dead crickets when food is scarce.
It is a popular myth that crickets emit the commonly heard ‘chirping’ noise, known as ‘stridulation’, by rubbing their legs together when this in fact is not the case. Only the male crickets produce this noise, and do so by using the stridulatory organ – which is a long vein that runs down the underside of each wing. In appearance, this vein looks a little bit like a comb, because of the presence of ‘teeth’, which the male rubs the topside of one wing to produce the chirping sound. Crickets are used as a food source in some countries such as Thailand and Vietnam and are thought to contain high levels of protein. Though several species are capable of delivering a fairly painful bite, crickets are generally completely harmless to humans, and are not venomous or poisonous, despite certain myths. They are preyed upon by many other animals, including spiders, salamanders, lizards and frogs.
There are over 900 species of cricket, many of which are often mistaken for grasshoppers due to the fact they share the ability to jump relatively high and long distances, because they have such powerful back legs that are designed for this very purpose. One main difference between these two species, however, is that grasshoppers are strictly diurnal, whereas crickets are always nocturnal.