Parischnogaster striatula

P. striatula has black pigmentation on its clypeus, with black inner and outer eye stripes, and mandibles. The adults are recognizable by their distinctive hovering flight.[3]

Their nests lack a nest pedicel, and implant on thread-like suspensions such as rootlets, thin stems and artificial wires.[4] They consist of cells spirally arranged around a central tube,[1] and are constructed from mud, mud mixed with chewed vegetable material, or paper.[3] P. striatula colonies do not contain many individuals, therefore the nests are small in size.

Two females of Parischnogaster striatula resting on their nest hanged on a small root

The colony consists of one dominant female, one or two other non-dominant females, and males. The dominant females are usually located at the top of the nest, with the non-dominant females in the middle, and males at the lower part of the nest near the entrance. There is no visual status badge among the females; females with developed ovaries look identical to females with underdeveloped ovaries. What separates the dominant females from the non-dominant females is the size of their ovaries. The female P. striatula with the largest ovaries becomes the dominant female of the colony.[1]

The dominant females are the ones that lay eggs and stay on the nest for the longest periods of times. The non-dominant females are usually the ones to construct the nest. They also forage for food and mud, which they use to build the nest.[1] The females are also very attentive to wasps approaching their nest, which they greet with either antennations and/or bites.[1] However, sometimes the roles can be temporary. Newly emerged females will most likely become workers by helping out with the nest before leaving to find or acquire their own colony.[3]

When laying eggs, P. striatula secretes a sticky abdominal substance, created by its Dufour’s gland, and collects it in her mouth. Then as the eggs emerge from her abdomen, she uses this abdominal substance to handle them and proceeds to stick them into an empty cell. Next, to secure her eggs, the female will once again gather more abdominal substance in her mouth and place it over the eggs. Sometimes, the female wasp that laid the eggs, will keep them uncovered and the worker females will finish the job with their own secretion. There have been cases where the female was interrupted during this process, and was seen abandoning the nest with the eggs still in her mouth. Once the threat passed, the female was able to return to place them in the empty cell.[6] Individuals in the colony are not able to discriminate between eggs covered by their nestmates.[1]

One main defensive strategy is their use of mimicry when building their nests. By blending into their surroundings, P. striatula is more likely to avoid confrontation with their predators. However, this strategy is not always successful. Their two main predators are hornets and ants. The females of the nest change their defensive strategy based on who is attacking them. When it comes to ants, the females are fiercely aggressive; they reject and bite the invaders. For hornets, they put on a threatening bending posture of the abdomen. A more useful strategy against hornets is the use of dropping flights.[1]