Top 20 Most Common Insects in Portugal

The speckled wood (Pararge aegeria) prefers to live in damp, dark woodlands. Unlike other butterflies, it's more active in shadier habitats rather than sunny ones. Males often fight over a perch, spiraling up to the treetops until they determine a winner. These perches are where the males find passing females.

The pine processionary (Thaumetopoea pityocampa) have very boring looking adult stages, as though they have to calm down after being major jerks in their caterpillar stages. Their caterpillars are known to be major pests that munch down many pine trees, hanging out in tent-like structures as they do so. They are also known to cause harmful effects on anyone foolish enough to touch their hairs.

Colias croceus has a wingspan of 46–54 millimetres (1.8–2.1 in). The upperside of the wings is golden to orange yellow with a broad black margin on all four wings and a black spot near the centre forewing. Usually these butterflies settles with its wings closed, consequently the black margin of the uppersides of the wings is difficultly visible. The underside lacks the black borders and is lighter, with a more greenish tint, particularly on the forewings. In the forewing underside is the same dark spot as on the upperside, but often with a light centre; the hindwing underside has a white centre spot, often with a smaller white or dark dot immediately above it. Sometimes, a row of black dots occurs on the underwings' outer margins, corresponding to where the black border ends on the upperside. Females differ from the males in having yellow spots along the black borders on the upperside. In flight, Colias croceus is easily identifiable by the intense yellow colouring, much brighter than that of the lemon-yellow male common brimstone which also lacks black markings. Like all Colias species they never open their wings at rest. In a small proportion of females (about 5%) the golden upperside colouration is replaced by a pale cream colour. These females have been distinguished as form helice. The pale form helice does not seem to be that distinct as intermediates exist and the variation is to some extent related to humidity during development, with dryer conditions producing paler colouration. These pale forms helice can be confused with Berger's clouded yellow (Colias alfacariensis) and the rarer Pale clouded yellow (Colias hyale). Even the palest C. croceus tends to have more black on the upperside however, in particular on the hindwings. Young caterpillars are yellow-green, with a black head. Later they become completely dark green, with a white red spotted lateral line after the third moult. The pupae are green and have a yellow side stripe. This species is rather similar to Colias myrmidone, Colias chrysotheme, Colias erate, Colias hyale, Colias alfacariensis, Colias caucasica, Colias aurorina.

Red admiral (Vanessa atalanta) is a visually striking species of butterfly. Unusually territorial, males will compete for choice areas, and females will only mate with males that maintain their own territories. This butterfly is known for being particularly patient with human interactions, even to the point of perching on clothing or flesh.

The greater stag beetle ( Lucanus cervus ) is popular with insect lovers. The male individual is known for the impressive jaws that look like antlers of a deer. In contrast, females do not have jaws and are much smaller. The adults feed on juices and tree saps while the larvae eat wood. By the way, greater stag beetles are considered a pest in the Middle East where they dig into the root systems of date palms, affecting the date crop.

Western honey bee（Apis mellifera） is the most common species of honeybee in the world. Among the first domesticated insects, its cultural and economic impact on humanity has been vast and far-reaching, providing honey, wax and its services as a pollinator. Western honey bee faces challenges worldwide, such as colony collapse disorder, and populations are thought to be decreasing.

The old World swallowtail (Papilio machaon) is commonly just called the "swallowtail," giving it the added title of "old world" to distinguish it and remind us that it comes from the "old world" (Asia, Africa, Europe). The upper side of them is a beautiful combination of pure white with black striping, the underside being a brownish version of the same thing. There is blue and two red dots on its back side.

Cabbage white (Pieris rapae) derives its common name from its habits as a caterpillar, which is a ferocious pest for cabbage, kale and broccoli farmers. In North America, it is one of the first butterflies to emerge in spring, heralding the beginning of the season.

The meadow brown (Maniola jurtina) is similar to the Gatekeeper in the way that it rests with its wings open due to the "eye spots" on either end of its wings that ward off predators. While the color is a deep brown, the caterpillar form is a beautiful bright green with little, white hairs and a dark line leading down its back.

Large white (Pieris brassicae) is visually similar but quite larger than its close relative P. rapae. It lays its eggs on food plants such as cabbages – the origin of its common name – leading to many farmers' classifying this species as a pest.