Adult yellow mealworms are shiny, sturdy, dark brown to black beetles and measure around 16 mm (14–18 mm) in length. They are the biggest insect pests to infest whole and ground grains. Males are usually smaller and slimmer than females.
Caddisflies look very much like small moths. Depending on the species, they range from 4 mm to 4 cm in length. They have long slender antennae and vestigial mouthparts that enable them to ingest liquid food only.
Two pairs of dark membranous wings, which are folded roof-like over the abdomen when at rest, are located on the thorax. The wings are covered with tiny hairs that give them a downy look.
The cylindrical abdomen usually tapers off to a pair of appendages in females and to at least two pairs in males.
Depending on the species, mayflies range from 2 to 18 mm in length, excluding the antennae and caudal filaments. They are often whitish or yellowish in colour.
Mayflies have vestigial mouthparts and are therefore unable to feed. The membranous and extensively veined wings are held vertically when at rest.
Mayflies have two to three long filaments at the tip of the abdomen. These have a tactile role, stabilize the insect’s flight and, together with the wings, help prevent joined mating couples from falling to the ground.
Bed bugs belong to the Cimicidae family. This family is composed of more than 100 species that feed on the blood of birds and mammals.
Two species live exclusively off humans: Cimex lectularius, which lives mainly in temperate zones, and C. hemipterus (F.), which is mainly found in tropical areas.
Before eating, bed bugs are brown or yellowish brown. Once they have fed on blood, they become reddish brown and resemble small apple seeds. Their heads include highly specialized piercing-sucking mouthparts. Generally, the tip of the male’s abdomen is pointed and the tip of the female’s abdomen is rounded.
Head lice are tiny wingless insects with a flattened body. They have three short pairs of legs equipped with claws that grasp the host’s hair.
Fleas are tiny, dark-coloured, wingless insects. They have a laterally flattened body and powerful long legs (especially the hind ones) well adapted for jumping.
Depending on the species, these elongate insects either have four wings or are wingless. Their long antennae are nearly half their body length. They are easily identified by the well-developed cerci located on the end of the abdomen. Females have long, straight-sided, stocky cerci, while males have narrower and strongly curved cerci.
These little insects are 1.5 to 12 mm long, with an oval but sometimes almost square or rectangular shape. The body is often somewhat flattened and shiny. Their colour varies from brown to black with irregular yellow-orange, yellowish or red marking.
The silverfish and firebrats that we find indoors belong to two species that are similar in shape, but not in colour.
Common silverfish (Lepisma saccharina) are wingless and have a flattened, carrot-shaped body. They have two long antennae on the head and three tail-like appendages at the tip of the abdomen. These insects are covered with metallic grey scales that give them their silvery colour.
Firebrats (Thermobia domestica) can be distinguished by their brownish beige colouring and light and dark markings that give them a mottled appearance.
Cockroaches are insects with a flattened, oval and brown or black body. The head is almost fully covered by the pronotum (part of the thorax shaped like a shield) and has two long, very mobile antennae.
These insects usually have two pairs of wings and an abdomen with two more or less developed appendages, called cerci.