Beetles have chewing, or mandibulate mouthparts. Mandibulate mouthparts can be used to chew vegetation, detritus, or prey. They have the same basic structure as cockroach (Order: Dictyoptera) and grasshopper (Order: Orthoptera) mouthparts
Hemiptera (Cicada) - Piercing and Sucking Mouthparts
Sucking mouthparts are modified into the form of a beak (or stylet) through which liquid food is sucked up. The mandibles are either elongate and stylet-like or lacking. Palpi normally found on chewing mouthparts are absent. The beak of the cicada (and all true bugs) is an example of the piercing & sucking form
Diptera (Mosquito) - Piercing and Sucking Mouthparts
As the stylet (composed of the labrum, mandible, hypopharynx, and maxilla) is inserted into the prey, the labium acts as a sheath and slides up out of the way. A fluid is secreted which acts as an anticoagulant
Diptera (Horsefly) - Biting and Lapping Mouthparts
Horsefly males feed on nectar and plant juices, but females feed on blood. They use their mandibles like scissors to slice open the skin, inject an anticoagulant, and lap up the blood with the modified labium
Diptera (House fly) - Sponging Mouthparts
During feeding the proboscis (modified labium) is lowered and salivary secretions are pumped onto the food. The dissolved or suspended food then moves by capillary action into the pseudotracheae (sponge) and is ingested. There may be sharp teeth on the pseudotracheae to rasp flesh and draw up blood. The labella is the fleshy distal end of the labium that functions as a sponge like organ to sop up liquids
Hymenoptera (honeybee) - Chewing and Lapping Mouthparts
In honey bees and bumble bees mouthparts are modified to utilize liquid food, honey and nectar. A central "tongue" is used to draw liquid into the body. The mandibles are not used for feeding but function to cut floral tissue to gain access to nectar, for defense, and for manipulating wax
Lepidoptera (Butterfly and Moth) - Siphoning Mouthparts
The coiled proboscis of butterflies and moths is composed of modified maxillae in which the galeae interlock to form a tube. When feeding the proboscis is uncoiled and extended into the flower. Nectar is sucked up into the mouth or oral cavity.
Hymenoptera - The Tentorium
The tentorium is the internal skeleton of the insect head. The tentorial pits (white arrows) are where the cuticle invaginates to form the internal skeleton. The tentorial arch or bridge (red 'x') forms attachment points for muscles controlling the mouthparts, and adds structural support against the force of the muscles. Without it, the head could cave in under the pressure!