Butterflies belong to the class Insecta. How many legs does an adult butterfly have?

Introduction / Context:
This question checks a very basic point of animal classification. Insects, including butterflies, are defined by several key structural features. One of the most important is the number of legs. Knowing how many legs butterflies have helps reinforce the broader idea of what characterises insects in general biology, making it a simple but frequently tested fact.

Given Data / Assumptions:

• The animal in question is the butterfly, specifically the adult stage.
• Butterflies are members of the class Insecta.
• The options list different possible numbers of legs: 2, 4, 6, 8 and 10.
• We assume a normal, fully developed adult butterfly without deformities.

Concept / Approach:
Insects are arthropods characterised by a three part body (head, thorax and abdomen), one pair of antennae, compound eyes and three pairs of jointed legs, making a total of six legs. Butterflies and moths belong to the order Lepidoptera within this class. All adult butterflies have three pairs of legs attached to the thorax, although in some species the front pair may be reduced or held close to the body, sometimes making them appear to have fewer legs at first glance. However, anatomically, they still possess six legs as typical insects.

Step-by-Step Solution:
Step 1: Recall the defining feature of insects: three pairs of legs, totalling six. Step 2: Recognise that butterflies are insects and therefore follow this general structural pattern. Step 3: Remember that even when some legs are smaller or tucked away, the total count remains six. Step 4: Compare this with spiders, which are arachnids and have eight legs, and with vertebrates that have two or four limbs. Step 5: Select six as the correct number of legs for an adult butterfly.

Verification / Alternative check:
Diagrams of butterfly anatomy in school science books clearly show three pairs of legs attached to the thorax. The same is true for other insects like ants, bees and grasshoppers. Classification charts summarise this: insects have six legs, arachnids have eight and crustaceans often have more. Since butterflies fall squarely in the insect category, there is no exception to this rule in standard teaching material.

Why Other Options Are Wrong:
Two legs and four legs correspond to typical vertebrate limb counts, such as humans and many mammals, not to insects.
Eight legs would fit spiders and scorpions, which are arachnids, not insects like butterflies.
Ten legs would apply to some crustaceans such as crabs and lobsters, but not to butterflies.

Common Pitfalls:
One pitfall is visual confusion in species where the front pair of legs is small or held in a way that makes it less noticeable, leading some people to think butterflies have four legs. Another issue is mixing up insects with spiders and assuming eight legs. To avoid these mistakes, rely on the basic rule that all true insects, including butterflies, have six legs, even if some may look shorter or different in shape.

Final Answer:
An adult butterfly has 6 legs, arranged as three pairs like all insects.