A Moth with a Big Snout and No Ears -- Also, Can Moths Hear? (includes 4 Macro Photos)

This moth, of the genus Pararguda, came for a visit a couple of nights ago. It is most likely P. nasuta. It belongs to a family of moths known as the Lasiocampidae, which go by various common names such as Eggers, Lappet moths, or Snout moths. There are no prizes for guessing which name is the most appropriate for this one. The labial palps are quite elongated and project straight out, giving the appearance of a long snout.

Can moths hear?

Many species of moth can hear. They have a tympanal organ (basically an ear drum) on the abdomen. However, not all moths have the ability to hear. In fact the poor old snout moth above, is totally deaf. This is probably because they have no need for a sense of hearing. For those moths that do have a sense of hearing, the primary benefit would be to detect bats. This requires an ear that can detect very high frequencies. Indeed the Greater wax moth, Galleria mellonella, has been found capable of detecting ultrasonic frequencies of almost 300 kHz. So, is the Snout moth at great risk of being preyed upon by bats? Not really. One study showed that atympanate moths (those without a tympanal organ) are generally on the wing at times when bats are least active.

The first photo below shows dorsal and ventral views of the moth. This image is made from three separate shots of the same moth, I did not line them up like that. Some may wonder about the welfare of the moth on it's back :-) The moth is actually alive and quite healthy. Some moths will drop to the ground and play dead as a defense mechanism. When this one dropped and played dead, it was a perfect opportunity to get the shot. It was in an open area and it it was free to fly away at any time. In fact, since releasing it, it has just sat there. As it is a female, it will no doubt be emitting pheromones and patiently waiting for a male to pick up the scent.

_{( All photos, videos, and text on this blog are by @mostly.nature )}
Click on images for a larger version

Pararguda sp n2 BY MV Light Tas 2017-09-26.jpg

_{Dorsal and ventral views of P. nasuta}

Pararguda sp n1 BY MV Light Tas 2017-09-26.jpg

_{The elongated labial palps of P. nasuta look like a long snout.}

Pararguda sp n4 BY MV Light Tas 2017-09-26.jpg

_{Lateral view of P. nasuta}

Pararguda sp n3 BY MV Light Tas 2017-09-26.jpg

_{Frontolateral view of P. nasuta}

References:

Yack J. E. (1988). Seasonal partitioning of atympanate moths in relation to bat activity. Can. J. Zool. 66, 753-755. 10.1139/z88-111
Moir, Hannah and Jackson, Joseph and Windmill, James (2013) Extremely high frequency sensitivity in a 'simple' ear. Biology Letters, 9 (4). ISSN 1744-9561

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