Beetles

Forewings modified into hardened elytra that protect the hindwings and abdomen.
Complete metamorphosis (holometabolous): egg → larva → pupa → adult.
Chewing mouthparts.
Largest order of insects (40% of described insect species).
Found in nearly all habitats except marine environments.

What are the defining characteristics of beetles (Order Coleoptera)?

Elytra are hardened forewings that protect the delicate hindwings and dorsal side of the abdomen.
Adaptation for survival in harsh environments and burrowing habits.
Allow beetles to inhabit niches other insects may not tolerate.

What is the function of elytra in beetles, and how does it represent an evolutionary adaptation?

Herbivores: leaf beetles, weevils.
Predators: lady beetles, tiger beetles.
Scavengers: carrion and dung beetles.
Wood-borers and decomposers: bark beetles.
Pollinators: some scarab beetles.
Roles: nutrient cycling, pest control, seed dispersal, pollination.

Describe the diverse feeding habits of beetles and their ecological roles.

Certain beetles, like Dermestidae and Silphidae, colonize decomposing bodies at predictable stages.
Used to estimate postmortem interval (PMI).
Can indicate time since death, movement of corpse, and environmental conditions.

What is the relevance of beetles in forensic entomology?

Long legs, fast runners, often metallic.
Predators of other insects, often used in biological control.
Mostly nocturnal.
Found under rocks, logs, or soil surface.

What are the distinguishing features and significance of the family Carabidae?

Oval, robust bodies; clubbed antennae.
Includes dung beetles, flower chafers, and June beetles.
Important in nutrient cycling through dung burial and decomposition.
Some species used in traditional medicine or cultural symbolism.

What are the characteristics and roles of Scarabaeidae beetles?

Brightly colored, often red with black spots.
Predators of aphids, scale insects, and other pests.
Used in integrated pest management (IPM).
Some species feed on plants and can be pests themselves.

What is the significance of the family Coccinellidae?

Often black or brown with thickened exoskeletons.
Larvae known as mealworms.
Found in dry, arid environments.
Feed on decaying plant matter and stored products.

What are notable features of Tenebrionidae beetles?

Feed on dried animal material: skin, fur, feathers.
Used to clean skeletons in museums (dermestid colonies).
Forensically important: late colonizers of decomposing remains.

Why are Dermestidae beetles important in museums and forensics?

Campodeiform: active predators (e.g., Carabidae).
Scarabaeiform: C-shaped grubs, usually herbivores (e.g., Scarabaeidae).
Elateriform: wireworms, slender and hard-bodied (e.g., Elateridae).
Apodous: legless larvae, often internal feeders (e.g., weevils).

Describe the different larval forms of beetles and their significance.

Dermestidae: feed on stored products, potential allergens.
Tenebrionidae: pests in stored grain.
Anobiidae: woodborers and product pests (e.g., drugstore beetle).
Blister beetles (Meloidae): produce cantharidin, a toxic compound.

Name some beetle families with species that are pests to public health.

Antennae shape (e.g., clubbed, filiform, lamellate)
Elytra texture and coverage.
Tarsal formula (number of tarsal segments).
Pronotum shape and sculpture.
Mouthpart orientation and type.

What are key morphological features used to identify beetles?