Blocking sensory input of flies - 2 questions

[Jorge SantiagoBlay]

Hi:

I wish to stop some flies from receiving extranal stimuli, as follows:

(of course, disrupting as least as possible other physiological functions):

(the flies are about 1-2 mm long)

1. Vision - want to make the flies blind (recall, the eyes are tiny, not to
mention the ocelli). Brushes and markers are too large. is there something
like a mini fountain pen that could produce a tiny, easy to regulate droplet?

2. Proboscis extension reflex. Wish to cut front legs (but that will possibly
render flies less able to walk) or cut proboscis (but that will render flies
unable to eat).

So far, I have tried wing removal, crowding (to possibly transfer cuticular hydrocarbons) and crowding, all with very little or no effect.

I need some suggestions on other sensory apparati that I may disturb (thus the
two mentioned above). Any other suggestions greatly appreciated.

Thanks.