Top 20 Most Common Insects in Cascais

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 adult males reach 2 - 4 mm in length, while females are 7 - 8 mm long. The two pairs of the front legs, used for hunting the flower-feeding insects, are more developed than the rear ones, which have a predominant motor function. Mature males have a black abdomen with two white marks. In mature females, the background colour of the abdomen can be red, yellow or white, with a black pattern which has been noted for a certain resemblance to the silhouette of Napoleon. Prosoma and legs are black or dark brown.

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.

Named for its striking pattern, european firebug is often described as the "firebug." It is known to congregate in large aggregations reaching as many as one hundred individuals at a time, particularly while still immature. Because they feed upon the seeds of lime trees, clusters of mating individuals can often be found at the bases of these trees in late spring.

The asian hornet (Vespa velutina) is a predatory species, preying primarily on deceased animals and arthropods, including honey bees. Because of this, it's a major pest for the beekeeping industry, weakening and destroying honey bee hives. The females have a stinger that can inflict pain on humans, but the males do not.

The egyptian locust( Anacridium aegyptium) is usually gray, brown, or olive in color has a mid-sized body with a pair of short and robust antennae on the head. It is generally regarded as a kind of minor pest as it essentially feeds on the leaves of various fruit trees in the orchards but does not cause serious harm to crops.

Crocothemis erythraea can reach a length of 3.5 - 4.5 cm. These dragonflies haves a flattened and rather broad abdomen. The adult male scarlet dragonfly has a bright scarlet red, widened abdomen, with small amber patches at the bases of the hindwings. Also the veins on the leading edges of the wings are red. Females and immatures are yellow-brown and have a conspicuous pale stripe along the top of the thorax.

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 painted lady is a migratory butterfly that spends part of the year in Northern Africa and then migrates to Europe during the warmer months. Although the adults feed on nectar from flowers, the larvae feed on the leaves of nettles and thistles.

The male is smaller than the female, the front wing of the male is 1.5 - 1.6 cm whereas a female front wing is 2 cm, and has a patch of scent-producing scales known as the androconia, which can be seen as a dark patch on the upperside of the forewing.