''Synoeca septentrionalis'' is one of five species of wasps in the genus ''
Synoeca''.
It is a swarm-founding wasp that is also
eusocial
Eusociality ( Greek 'good' and social) is the highest level of organization of sociality. It is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generations wit ...
,
exhibiting complicated nest structure and defense mechanisms
and a colony cycle including a pre-emergence phase and a post-emergence phase.
It is typically found in areas from Central to South America.
This wasp is one of the larger species of
paper wasps and exhibits multiple morphological adaptations as a result of this.
''Synoeca septentrionalis'' is known for possessing a very painful sting.
Taxonomy and phylogeny
''Synoeca septentrionalis'' is one of five species of wasp in the genus ''Synoeca'', with the other four being ''S. chalybea'', ''S. cyanea'', ''S. surinama'', and ''S. virginea''.
Wasps in the genus ''Synoeca'' are often referred to as warrior wasps and are found in various areas in the Americas. Each wasp in the genus exhibits similar characteristics, but from a phylogenetic standpoint, ''S. septentrionalis'' is most closely related to ''
S. surinama'' and ''
S. cyanea''. The wasps in this genus are also a part of the paper wasp tribe known as
Epiponini
The Epiponini (formerly known as Polybiini) are a large and diverse tribe of social wasps inhabiting the Neotropical region, with some species' ranges extending into the Nearctic
The Nearctic realm is one of the eight biogeographic realms ...
, which are
Neotropical
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone.
Definition
In biogeogra ...
.
In general, the genus is quite aggressive
[Hogue, Charles Leonard. ''Latin American Insects and Entomology''. University of California Press, 1993. ] and will often display cohesive defense mechanisms when threatened.
Description and identification
''Synoeca septentrionalis'' exhibits a blackish or dark blue color and has a metallic-like appearance.
Their wings are also quite large and are entirely
infuscate.
Their metasomal tergum (a portion of the abdomen) and
sternum
The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major bl ...
both exhibit erect hairs, and their
clypeus is imprinted with an area that resembles a dark triangle.
Color patterns vary among the species; some exhibit a reddish color, while others are completely darkened.
Overall, they are a medium-sized wasp
with lengths of approximately .
They are considered to be
paper wasps, as their nests are made out of paper.
Their nests will change as a colony grows. Typically, they will start as one comb within a ridged, domed envelope that also has a hole or holes where other lobes can be added as necessary.
Most nests have only two to three lobes, but nests with nine lobes that span over three meters have been reported.
Occasionally, some of the holes will be paired as two, and, combined, they have a perimeter of .
Certain holes will remain open and act as entrances or exits for ''S. septentrionalis''.
Distribution and habitat
''Synoeca septentrionalis'' is a
Neotropical
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone.
Definition
In biogeogra ...
species found in
Central and
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
, especially in areas such as
Costa Rica
Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...
,
Panama
Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...
,
Colombia
Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...
,
Guatemala
Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...
,
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
and
Venezuela
Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...
.
Its distribution extends further north than others in the genus.
These wasps often build their nests on trees, specifically flat against a tree trunk or a limb.
Nests have been seen between 1.70 and 6 meters above the ground.
Colony cycle
As a swarm founding species,
''S. septentrionalis'' travels and founds new colonies as a large group.
In ''S. septentrionalis'', nest construction will begin when the swarm has all arrived at the potential construction site.
This marks the beginning of the pre-emergence phase.
Construction is typically done by a group of workers, and, by the time the nest is completed a few days later, eggs will have been laid in the cells by the queen.
Roughly a week after the nest is complete, the first larvae begin to hatch, and these will become adults approximately 30 days after hatching, marking the end of the pre-emergence phase and the beginning of the post emergence phase. It is at this point when the emergence of workers is largely dependent on the necessity to produce reproductive females that will become queens. Because ''S. septentrionalis'' is a polygynous species, more than one queen will exist at a given time, and often the number of queens will fluctuate. When queen number is small, the ratio of queens to workers will be low and thus the queens will have difficulty suppressing reproduction in subordinate females, of which some will become additional queens. When queen number is high, the ratio of queen to workers is higher, and suppressing reproduction in subordinate females is easier.
Normally, in wasps residing in a temperate climate, the nesting cycle and the colony cycle are one and the same, meaning that a colony will use one nest per reproductive episode. However, species such as ''S. septentrionalis'' primarily reside in a tropical climate, and this congruency is disrupted, as they may stay in the same nest for more than one reproductive cycle. As a result, they exhibit an "intermediate nesting cycle", in which the benefits of staying in the same nest for another colony cycle outweigh the costs of staying in the nest.
Behavior
Movement between nest sites

It has been seen that, when moving as a swarm between nests or to a new nest, ''S. septentrionalis'' will use various means of communication to facilitate group movement.
This is most often done through the use of pheromones.
When moving from an old to a new nest site, the wasps will rub glands located on or near their gasters on various spots between the nest sites.
These creates a trail of chemical pheromones between the two sites that the wasps are able to follow.
Along with this "gaster-rubbing," ''S. septentrionalis'' will often chew and lick leaves on the pathway between the two sites,
thus enhancing their methods of communication. ''
Polybia sericea
''Polybia sericea'' is a social, tropical wasp
of the family Vespidae that can be found in South America. It founds its colonies by swarming migrations, and feeds on nectar and arthropods.
''P. sericea'' is medium in size, and has a dark-colore ...
'' is another species that moves between nest sites using pheromones.
Nest entrances and exits
''S. septentrionalis'' is unique to the genus ''Synoeca'' in that its nests will typically contain two entrance or exit holes, whereas the nests of other species in the genus will usually only contain one hole. Within the nests, the wasps will often choose one hole as a preferred "entrance point" and another as a preferred "exit point" as opposed to entering either one at random. It is likely that determinations for which hole to use as an entrance or exit arise as a result of the behavioral patterns and the efficiency with which each individual hive operates.
Adaptations relating to body size
The wasps within the family Vespidae exhibit a wide range of body sizes, and ''S. septentrionalis'' is one of the larger wasps within the family. As a result, they are able to generate a lift force that is able to maintain flight in the presence of their large muscle mass. In order for this to occur in the most efficient manner possible, these wasps have enlarged wings and veins that are distally extended. The elongated wings allow for flying that is more energetically efficient, in order to compensate for their large body size and muscle mass, while the distally-organized veins prevent bending of the wings, which would result in a loss of energy.
Kin selection
Cyclical oligogyny
''Synoeca septentrionalis'' exhibit a behavior that is known as "cyclical oligogyny," where there are varying numbers of queens per colony cycle. When the number of queens becomes low within a colony, they will signal to new females for them to try to become queens and repopulate the nest with queens. As evidence of this, it has been found that in most swarming colonies such as ''S. septentrionalis'', the population of queens is bimodal with respect to age; some queens are very old while others are very young.
Physiological differentiation
Because morphology differences cannot dictate caste differences in ''S. septentrionalis'', due to morphological similarity, castes are determined by adult disputes as opposed to manipulation at the larval stage. In colonies with already-established queens, workers will display aggressive behavior in order to inhibit female ovary development. Females with limited ovary development exhibit stringed, filamentous ovaries that do not have a mature oocyte and cannot contain sperm. When workers are not preventing female development, they are raised in an orphanage-like manner where they are able to develop full ovaries with multiple oocytes that can maintain sperm. These are ultimately the females that are able to take a chance to become a queen.
Interactions with other species
Predation
''Synoeca septentrionalis'' is preyed upon by numerous species. This is largely because it resides at an elevation of 300 meters above sea level, a lower elevation than most paper wasps.
Specifically, army ants will regularly feed on them along with other species of paper wasps.
This prevalent predation has resulted in ''S. septentrionalis'' making numerous adaptations, some of which include forming a complex nest structure, choosing a nest-site that reduces exposure to predators, and establishing defensive mechanisms.
''S. septentrionalis'' has also been known to defend against army ants by piling their bodies up against the nest entrance.
However, army ant predation can be extreme enough to regulate the density of a colony and keep populations of ''S. septentrionalis'' and other species of paper wasps regulated.
Colony defense
The defensive behavior in ''S. septentrionalis'' often involves a large number of workers leaving the nest in order to display or attack with their stingers in response to a disturbance. Often, after the wasps leave the nest, they will display their
gaster in such a way that it is perpendicular to the ground and the rest of their body; this behavior is defined as gaster-flagging. From a defensive standpoint, it is likely that gaster-flagging serves as a warning signal to predators that ''S. septentrionalis'' will engage in defensive stinging behavior if necessary. Likewise, gaster-flagging could potentially serve as a visual communication method between other members of the colony in order to mobilize them in the presence of a threat.
Along with gaster-flagging, ''S. septentrionalis'' will warn the colony when it is disturbed by drumming the inside of the nest, creating a characteristic alarm sound. To make the sound, the wasps scrape their
mandibles
In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla).
The jawbone i ...
across the nest walls. This is a characteristic defensive mechanism that all species of the genus ''Synoeca'' exhibit.
Commensalism with Montezuma oropendola
The
Montezuma oropendola
The Montezuma oropendola (''Psarocolius montezuma'') is a New World tropical icterid bird. It is a resident breeder in the Caribbean coastal lowlands from southeastern Mexico to central Panama, but is absent from El Salvador and southern Guatemal ...
(''Psarocolius montezuma'') is a tropical bird that shares a similar distribution to ''S. septentrionalis''. It has been observed that more of these birds will nest in trees that are tall, umbrella-shaped, and exhibit a presence of wasps, specifically ''S. septentrionalis''. The wasps will utilize their defensive mechanisms and stings in order to deter both predators and ectoparasites. As a result, ''S. septentrionalis'' can exist in a commensalistic relationship with Montezuma oropendola.
Human importance
Stings and venom
This wasp species has an incredibly painful sting. On the
Schmidt sting pain index
The Schmidt sting pain index is a pain scale rating the relative pain caused by different hymenopteran stings. It is mainly the work of Justin O. Schmidt, who was an entomologist at the Carl Hayden Bee Research Center in Arizona.
Schmidt's or ...
it is ranked 4 out of a possible 4, on par with the sting of a
bullet ant
A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constru ...
.
Justin Schmidt, the author of the index wrote of the sting in his book ''The Sting of the Wild'' - "Torture. You are chained in the flow of an active volcano. Why did I start this list?",
Similarly, out of a possible 4 points on the
Starr sting pain scale
The Starr sting pain scale was created by the entomology, entomologist Christopher Starr as a scale to compare the overall pain and nociception, pain of hymenopteran stings on a four-point scale, an expansion of the Schmidt sting pain index, "pain ...
, ''S. septentrionalis'' received a 4, a rating attained by very few other species assayed. A 4/4 on this scale means that the sting is considered to be "traumatically painful" and often requires some medical attention.
References
External links
American Insects - ''S. septentrionalis''
{{Taxonbar, from=Q14425144
Hymenoptera of South America
Insects described in 1978