Acrobat ants

Description:

Crematogaster is an ecologically diverse genus of ants found worldwide, which are characterised by a distinctive heart-shaped gaster (abdomen), which gives them one of their common names, the Saint Valentine ant. Members of this genus are also known as cocktail ants because of their habit of raising their abdomens when alarmed. Most of species are arboreal. These ants are sometimes known as acrobat ants. Acrobat ants acquire food largely through predation of other insects, like wasps. They use venom to stun their prey and a complex trail-laying process to lead comrades to food sources. Like many social insects, they reproduce in nuptial flights and the queen stores sperm as she starts a new nest. (information from Wikipedia)

Habitat:

Suburban flowerbed

Notes:

Re: 1st image - People who observe or study social insects understand what's going on here. These acrobat ants (Crematogaster sp.) are engaging in trophallaxis. Here's how it's defined by Wikipedia: "Trophallaxis is the transfer of food or other fluids among members of a community through mouth-to-mouth (stomodeal) or anus-to-mouth (proctodeal) feeding. It is most highly developed in social insects such as ants, termites, wasps and bees. The word was introduced by the entomologist William Morton Wheeler in 1918."