Proboscis Definition

Butterflies and moths are examples of Lepidopterans. Many have maxillary galeae, which are converted into a sucking apparatus called proboscis when they reach adulthood. The butterfly in the illustration above has a proboscis that looks like a coiled structure under its head.

The proboscis of a lepidopteran consists of one to five segments and is normally coiled when not in use. When the insect starts to suck up and eat, it uncoils and expands like a “sipping straw.” The butterfly in the image above is sucking nectar from flowers using its proboscis.

Two galeae make up the proboscis. Lepidopteran proboscises have a variety of morphological characteristics that reflect their varied feeding behaviours.

Hawkmoths, for example, have extended proboscises that allow them to enter their proboscises into the long tubular blooms and access the nectar within. The proboscis tip of nectar-feeding lepidopterans is very basic, lacking spines and having few sensilla.

Non-flower-feeding lepidopterans, on the other hand, have piercing proboscises that feed on the liquids of decaying fruits and animal fluids. The tip of their proboscis has “spines” and many sensilla.

Some noctuid moths, for example, have a “spiny” proboscis that allows them to puncture the fruit rind and drink the juice. The Asian vampire moths puncture the skin of their animal prey with their sharp proboscis and sip the blood.