WHY don't mosquitoes carry HIV?

When a mosquito bites, it injects saliva containing special substances, not blood from a previous bite. HIV cannot develop in a mosquito or any other blood-sucking insect. 

 In many cases, however, an insect attack can result in more than just allergies. Mosquitoes carry such unpleasant diseases as Rift Valley fever, yellow fever, Lyme disease, Dengue fever, Zika virus, leishmaniasis and, obviously, the well-known malaria.