I was browsing through some literature about color-changing in chameleons and stumbled upon this relatively recent paper about how chameleons will change color where mosquitoes bite them.

From the discussion:

While determining the particular mechanism(s) of color change is outside the scope of the current study, we nonetheless serendipitously discovered multiple instances of mosquito bite-induced color change in wild chameleons. This demonstrates that citizen science can produce discoveries of previously unknown natural phenomena, as our study represents the first formal documentations of mosquitoes feeding on chameleons as well as chameleon color change induced by arthropod hematophagy. These findings provide additional insights into the parasite-host interactions, such as the mosquitoes feeding on sleeping chameleons and particularly at the mouth.