Top 20 Most Common Insects in Porto

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.

The larva feeds on Prunus amygdalus (almond), P. persica (peach), P. insititia (a kind of plum), P. longipes, Pyrus communis (common pear), Malus domesticus (apple) and Crataegus oxyacantha.

The body length of larvae is variable and highly dependent on environmental conditions. The final stage (F-0-stage) larvae are 3.5 - 4.5 mm and weigh about 4 mg, slightly below the banded demoiselle. Calopteryx virgo can reach a body length of 5 - 5 cm, with a length of hindwings of 3 - 4 cm. These large, dark damselflies have small hemispherical eyes located laterally on the head, two pair of wings similar in shape and a slender abdomen. The basal area of the wings is transparent, otherwise wings are uniformly colored. The wings are also traversed by a dense network of veins. This species presents an evident sexual dimorphism in colour pattern. The male usually has much more extensive pigmentation on the wings than other Calopteryx species in its range: in the south east of its range (the Balkans and Turkey) the wings are entirely metallic blue while in other areas, there are clear areas at the base and tip of the wing. Immature males show brown wings, as the metallic blue wing color develops only with age. They have metallic blue-green bodies and blue-green eyes. The female has dark brown iridescent wings, a white patch near the tip of the wings (called a pseudopterostigma) and a metallic green body with a bronze tip of the abdomen.

The double-striped pug (Gymnoscelis rufifasciata) is a moth of the family Geometridae. It is a widespread and common species, being found throughout the Palearctic region, including the Near East and North Africa. This is a variable species but always easy to recognize due to the two prominent dark fascia across each forewing which give the species its common name. The forewing ground colour ranges from light to dark reddish brown. The crosslines are distinct. The inner margin of the pale white sub-marginal line bears black marks. The hindwings are pale grey with darker fringes, darker lines and a small black discal spot. There is a dark band across the basal segments of the abdomen. The wingspan is 15–19 mm. Two, sometimes three, broods are produced each year and the adults are on the wing in April and May (sometimes earlier), July and August, and sometimes later in the autumn. Later broods are more heavily marked. It flies at night and is attracted to light and flowers, both of its food plants and others. The larva feeds on the flowers of a huge range of plants (see list below) and has also been known to feed on the larvae of other lepidoptera. The species overwinters as a pupa.

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.

Calopteryx haemorrhoidalis can reach a body length of about 1.8–1.9 in. The abdomen length is of about 1.3–1.7 in in males, of 1.2–1.7 in in females. The length of the wings is of 0.91–1.26 in in males, of 0.98–1.46 in in the females. The males have a dark, metallic shining body, the color of which can be red-violet, golden or copper-colored. On the underside of the last three abdominal segments there red area, the so-called "red lantern" (hence the Latin species name haemorrhoidalis, meaning "blood flow"). The wings of males show a large dark area, while the females have a brown band to the wing tip and a metallic-green to bronze-colored body, with a brown belt on the back.

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.

The upperside forewings are a bright orange with a dark outside edge border and with eight or nine black spots. The hindwings are dark with an orange border. Some females also have a row of blue spots inside the orange border and are known as form caeruleopunctata. The undersides are patterned in a similar way but are paler. The black spots on the forewings are outlined in yellow and the dark colouring is replaced by a pale brownish grey. The hindwings are the same brown/grey colour with small black dots and a narrow orange border. The caterpillars (larvae) are usually green, but some have a purple stripe down the middle of the back and along each side.

Contrary to what you may believe of its name, the gatekeeper (Pyronia tithonus) is a butterfly, not a heavily armored guard standing at an iron fence. The gatekeeper seems to have its own gate based on weather, as it cannot survive well in colder climates. It also survives through the two eyespots on the end of each of their wings, protecting them against bird attacks.

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.