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To: "MWForum" <mwforum@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Subject: Moth_path
From: "Mike Sandy" <mjsandy@xxxxxxxxxxxxxx>
Date: Thu, 11 Jan 2007 20:03:18 -0000

Seymore Papert's paper An exploration in the Space of Mathematical Exploration
is stimulating (thanks Daniel). It made me think about Gary McCallister's
mosquitohunter.mw2 program. I wondered if the simulated behaviour of a
looking for prey or male moth seeking a female moth, could be made
more realistic. In the case of the moth, the male is attracted by the
pheromones released
by the female. It seems reasonable to assume that the male is following a path
governed by
an increasing concentration of the pheromone. Both mosquitoes and moths have 2
projecting in front of the head, which are likely to be the concentration
The insect should detect differences in strength of scent between the two
antennae and 
thus be able to move towards the higher value.
This means, in effect, that solid objects are of no consequence to the insect
in so much as the object distorts the scent distribution. 
Given the antennae are of fixed length and fixed angle of separation (the
latter for the
convenience of programming), 'mosquitohnter' can be recast as a distance
detector only,
i.e. 'towards' is unnecessary.
How to represent the variation of scent concentration? One way, is to show
this by 
a variation in colour (as for the height variation on a map). 
The detection is done on the attached program using a hidden turtle (called
The searching turtle itself could be used, but this makes it rather agitated.
The sensing is restricted because MW Pro colours are limited to 0.1 increments.


The females of blood sucking species locate their victims primarily through
They are extremely sensitive to the carbon dioxide in exhaled breath and
through the pores, as well as several substances found in sweat.

Attachment: moth_path.mw2
Description: Binary data

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