DECEMBER
1994

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

12-08-94

'Nosy' Insects Mind Own Business

What do elephants, Jimmy Durante and some insects have in common? The answer is, they all have a proboscis.

Technically, a proboscis is any tubular process on the head of an animal. The trunk of the elephant and the protruding mouths of some insects certainly fit the criteria. We also use the term proboscis as a humorous term for the human nose. That is especially true when the nose is a bit larger than normal. Such was the case with the famous schnoz of Jimmy Durante.

The proboscises of insects can generally be grouped into three types. There is the piercing-sucking type of proboscis. This design enables the insect to extract liquids from within a living organism. Some plant bugs pierce plant tissue and imbibe sap from the plant. Aphids also are sap suckers and, in the process, sometimes damage plants by taking a bit more sap than the plant can stand to lose.

Mammals, including humans, also are susceptible to losing fluids such as blood due to feeding of some insects bearing proboscises. Some lice are called sucking lice because they use their proboscises to suck blood from the host. Female mosquitoes have a proboscis that is used to procure a blood meal from some unlucky animal.

Some flies, such as the house fly, have a proboscis that is equipped with a sponge-like device on the bottom. Such insects are considered to have sponging-siphoning mouthparts.

Weevils are insects that have their chewing-type mouths extended from their heads on a Jimmy Durante look-alike snout. Weevils sometimes are called snout beetles because of their proboscises.

Undoubtedly the most recognizable of the insect proboscises belong to the Lepidoptera. Adult butterflies and moths have coiled tubes that are used to procure nectar and water. These are siphoning mouthparts and are similar in structure and appearance to the party blowouts so popular at New Year's celebrations. The insects use their siphoning proboscises like soda straws to sip nectar from a flower.

The extended mouthparts of some butterflies and moths are as long as the body of the insect. Such super nectar sippers allow insects to get the last drop of nectar from the deepest recesses of flowers. In fact, some flowers depend on these insects for pollination, and Charles Darwin once predicted that an insect possessing a 5-inch proboscis had to exist because he had discovered a flower where a tube that long was needed to extract the nectar. Many years later a moth with just such a proboscis was discovered.

Proboscises in both humans and insects vary widely. One thing is clear, however. Insects, unlike many humans, do not go around sticking their proboscises in other peoples' business!

 

Writer: Tom Turpin
Editor: Andrea McCann