page_title: Parischnogaster jacobsoni
section_title: Against small intruders
hierarchical_section_title: Parischnogaster jacobsoni / Nest defense / Against small intruders
caption_attribution_description: English: Ants guard of a Parischnogaster Jacobsoni nest.
context_page_description: Parischnogaster jacobsoni is a species of social wasp within Parischnogaster, the largest and least known genus of Stenogastrinae. It is distinguished mainly by its tendency to construct ant guards on its nests. Natural selection has led this wasp to have a thick substance emitted from its abdominal glands that allows it to protect its nest from invasions. Parischnogaster as a genus has been relatively unstudied; P. jacobsoni is one of the few investigated species because it has sufficient durability to live near human populations and it has demonstrated unusual resilience to pollution. While P. jacobsoni is a more complex organism than other wasps in Parischnogaster, the genus overall is relatively primitive with respect to social wasps as a whole.
context_section_description: The main physical defense to the nest is the ant guard. Wasps that build their nests on the underside of leaves will add an ant guard to the stem to prevent ants from attacking the nest. Ant guard construction is a behavior peculiar to P. jacobsoni among its genus, although it does occur in some wasps in the genera Eustenogaster and Liostenogaster via a radically different behavioral mechanism. In P. jacobsoni, the ant guard construction is simply a smear of secretion from the Dufour's gland on the nest that forms a sticky obstacle to ants attempting to invade the cells; this prevent ants from attacking, which differs from other social wasps that actually construct physical impediments to ants. The ant guard is always added to protect the nest, however, and immediately following the building of the first cell, the ant guard is laid down by the wasp.
  The wasp will defend the nest from conspecific intruders as well. When defending the nest from other flying objects, as soon as some flying movement is detected, the resident wasps begin to follow the object. If the object is small enough to be a conspecific wasp intruder, resident females will begin to buzz their wings and batter it in midair.
caption: Ant guard of a Parischnogaster Jacobsoni nest.
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