They can deal with the chemical defences in the latex, which does not cause the problem of mouthpart coagulation.
From the en.wikipedia.org
The new needle has an inner diameter of around 25 microns and an external diameter of 60 microns, which is about the same size as a mosquito's mouthpart.
From the newscientist.com
The gut contents, wing structures, and mouthpart morphologies of fossilized beetles and flies suggest that they acted as early pollinators.
From the en.wikipedia.org
Furthermore, the gut contents, wing structures, and mouthpart morphologies of fossilized beetles and flies suggest that they acted as early pollinators.
From the en.wikipedia.org
It inserts its piercing mouthpart called a stylet into the vascular system of the plant like a needle, removing the sugary food produced during photosynthesis.
From the timesunion.com
More examples
Any part of the mouth of an insect or other arthropod especially one adapted to a specific way of feeding
(Mouthparts (arthropods)) The mouthparts of arthropods have evolved into a number of forms, each adapted to a different style or mode of feeding. Most mouthparts represent modified, paired appendages, which in ancestral forms would have appeared more like legs than mouthparts. ...
(mouthparts) The appendages of the head used for feeding, including the labrum, hypopharynx, mandibles, maxillae, and labium.
(Mouthparts) Structures or appendages near the mouth, adapted for use in gathering or eating food.