These posts feature interesting observations I have found when going through my camera roll that I may not have noticed before.
A few days ago, I was looking at my phone background and noticed some interesting hairs on a picture of a Pheidole major and was curious so I looked into what they might be.
In this case, the observation was made on a Pheidole obscurithorax major In College Station, TX. Let's take a look at the photo, shall we?
If you take a close look at the major's mandibles, you might be able to see a few hairs sticking out.
Here's a tighter crop for better viewing.
At first, I thought these hairs were trigger hairs, like those present in Odontomachus and other trap-jaws. Trigger hairs are present in trap-jaw ants and cause the mandibles to snap shut with disturbance. They are used primarily for predation and sometimes transportation (when the ants launch themselves with their jaws).
An excellent example of trigger hairs as seen in this image by Alex Wild shows trigger hairs in an Odontomachus coquereli worker's jaws.
I first thought that these trigger hairs were possibly present on the pheidole as well, but after further inspection, the hairs do not appear to stem from the inside of the mandibles like on trap-jaw ants. Instead, they appear to be some sort of sensory hair used to detect objects carried by the major.
As you can see here in this specimen image, the hairs protrude from the front and back of the mandibles
Any underlined text should take you to its relative webpage. In addition, all images not belonging to me are linked to their respective sources.