Siphoning mouthparts are found in butterflies and some moths (Lepidoptera). The probiscis (galea) is a modification of the maxillary galea found in the more primitive madibulate (chewing) mouthparts, as seen in the cockroach. Compare the above diagram with the cockroach maxillae. The probiscis consists of paired galea which, during feeding, fit together to form a tube that is used to suck up nectar (it acts like a straw). When not in use the proboscis is coiled and held close to the underside of the head.The Morgan's sphinx moth, Xanthopan morgani, has the longest proboscis at 30 to 35 cm in length.
The labial palps have a sensory function and in some nocturnal moths they are used as hearing organs.