Monday, 13 June 2011

A Flying Seed-cracker, Broughton's Snout-nose

Over the course of the year we find a number of insects at the lights that really are out of place in the rainforest.
Broughton's Snout-nosed Katydid, Euconocephalus broughtoni Bailey, is one such insect. This katydid lives in grassy verges. it is most commonly found along roadsides. Every so often one or more show up at the light indicating that this katydid does some high altitude flying at night. (This is similar in some respects to the behaviour of the Pygmy Grasshopper mentioned in a previous blog.) For a katydid, this species is rather robust and you would think it incapable of long flights.

This is an uncommon katydid. It is a member of the tribe Copiphorini of the large and varied tettigoniid subfamily Conocephalinae. Other members of this tribe are more common. Several species of Pseudorhynchus are more commonly encountered in similar ecological situations.

The slant-face of this and most other copiphorines seems adapted for two activities. Feeding is one and the other may have to do with escape strategy, at least in some of these grass-feeders.

When threatened, they dive deep into the grasses and stick their heads in the substrate. The protruding part of the katydid resembles a blade of grass or a dead stem. They remain motionless in this position until the danger passes.

The mandibles are formidable and the katydid can deliver a painful bite that draws blood suggesting it must be a carnivore. But it is not. The head is full of powerful muscles that are used in cracking the tough seed coats of the grasses the katydid eats.

Note that the mandibles are not bilaterally symmetrical. The seed is probably positioned on one side and then cracked on the other. Also note that the maxillary palps are positioned just in front of the mandibles. These structures contain many sensory hairs that relay the message to bite.

Also note the pair prongs between the first pair of legs. These are often present in katydids and can vary in length and width depending upon the species. Their function is not known.

The reason for this blog is to present the Calling song of this katydid. It is similar to the songs of many Pseudorhynchus species but quite different.
The sound is produced by stridulation. On the underside of the left forewing, where the arrow points, is a file. It resembles the teeth of a comb. Through rapid back and forth movements of the wings, the file moves over a modified vein on the right wing, and the sound is produced. The structure of the wing is of the utmost importance in producing the right sound. Females are attracted only to males that they recognise. In this group, only males produce sound.


Alex said...

I love that head-on portrait!

Mr. Smiley said...

Thanks Alex

Patricia K. Lichen said...

Yes, amazing photos as usual!