The Elements of Evolution (49-10-4) Stingers

 Stingers

If you felt the pain right away, you would react and swat the insect away before it finished injecting its venom. ~ Indian American mechanical engineer Bharat Bhushan

Insect stings are memorable experiences, as they are meant to be by their givers. To deliver the maximal message, stingers are ingeniously engineered, with a soft tip that stiffens close to an insect’s abdomen.

Wasps and bees don’t want to create too much pain to start with. The softer tip makes it less likely that you’ll notice the initial insertion. ~ Bharat Bhushan

Stingers are ~7 times more elastic at the tip than at the base. The gradient in hardness and rigidity along the length of the stinger helps it penetrate as deep as possible while maintaining its integrity.

The stingers of wasps and bees differ in some ways. For one, wasp stingers are curved, whereas bee stingers are straight. But they have much in common.

The stingers of both have 2 serrated lancets that project from the end of the stinger. The lancets move back and forth to pierce the skin – a massaging motion that loosens the skin to open it up. A channel between the 2 lancets delivers venom.

Stingers have a clever design to optimize the mechanical properties without being too heavy. ~ Bharat Bhushan

The stinger cuticle is a laminated microstructure. Stingers have ideally placed hollow spaces to reduce weight while maintaining the strength necessary to penetrate thick skin.

The stingers really are elegantly designed and mechanically durable. ~ Bharat Bhushan

Stinging is also accomplished with precision. Bees and wasps sting at the most efficient angle for penetration: 10° for a wasp and 6° for a bee. These sting angles indicate why wasp stingers are curved and bee stingers straight.

Similar considerations were at work in the designs of spider fangs and scorpion stingers, which have distinct engineering characteristics that deliver utmost impact.