I first misread and thought these were some Ophiocordyceps unilateralis, the ones that feed on insects and make them climb to high places so the parasite can Burst open to spread its spores.
They're quite small, the females are often flightless and without limbs, they conceal themselves under domed scales for protection. They like to suck the sap from plants, some ant species will 'farm' them for the honey dew they secrete. Some species are pests and can infest and damage the plants they feed on, while others can be used commercially....checkout one of my other posts here The oldest fossils found date to the early cretaceous.