The leaf-footed stinkbugs have quite a few eye-catching body features including highly specialized mouthparts, offensive and defensive adaptations. This is an order of insects on which evolutionary pressures are visibly active shaping their morphologies. The evolutionary trade-offs underpinning these structures are an active research subject by biologists.
Here, three characteristic body parts in leaf-footed stink bugs are highlighted: The labium, the pronotum and the components of the hind leg (femur and tibia). Entomologically, the femur and the tibia are the third and fourth segments in insect legs.
The multi-segmented fruit piercing and drilling mouthpieces making up the labium is a fascinatingly successful feeding adaptation the magnolia leaf-footed bug (Leptoglossus fulvicornis) has evolved. The labium allows tapping a very rich resource: The developing seeds inside numerous aggregated follicles making the magnolia fruit.
There is an intense level of competition among the males of this insect. Males gather around receptive females and contest for winning a chance to mate. The reinforced pronotum that appears like a cape draping over the shoulder/thorax of the insect has evolved as a defensive structure in these males. Pronotum is an expensive tissue and requires rich resources to produce. Indeed, When the pronotum of the males were reinforced artificially, the winning outcomes of intra-male fights changed favorably.
The hind leg of the leaf footed stink bugs have two roles. The femur is a weapon in male-male fights. You can see the femur in action in an Acanthocephala terminalis mating aggregation on a thistle flower. The tibia on the other hand, is a deceptive defensive structure evolved to escape visual predators. The tibia is deceptively wide grabbing the attention of the attacker. When faced with an attack the insect can self-amputate the entire hind leg through a process called autotomy. Akin to the abscission in plants, this character has evolved independently a few times throughout the animal kingdom.
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