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Microstigmus

Microstigmus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Suborder: Apocrita
Superfamily: Apoidea
Family: Crabronidae
Genus: Microstigmus
Ducke, 1907

The thin-waisted social wasps (genus Microstigmus), which typically reside in neotropic regions from Central to South America, are a small genus of wasps that build nests and live in colonies ranging in size from 1 to 18 members.Microstigmus is widely considered to be the only true eusocial species within the Crabronidae family. Like all Hymenoptera, Microstigmus has an interesting sex determination pattern. Females are 2n (diploid), spawning from eggs that have been fertilized, while males are 1n (haploid) and spawn from unfertilized eggs. Female wasps contain the eggs within their egg sac and have the option of fertilizing them or not, thus having complete control of the gender of their offspring. This wasp genus, part of the suborder Apocrita, is distinguished physically by the narrow waist (petiole) between the end segment of the thorax (mesosoma) and the beginning of the abdomen (metasoma). Specifically, it is in the subgroup of "apoid wasps", those that exhibit social behavior in nesting and foraging. Evidence does exist that in some species social altruism is visible; however, studies on these topics have been limited. The small size and enclosed nest structure makes it difficult to obtain significant data. Although it was originally classified under the Sphecidae family due to its elongated petiole, Microstigmus has been reclassified into the new Crabronidae family.

Like all insects, the wasps of this genus have three body segments, with an exoskeleton covering the internal organs in each of them. The species of Microstigmus ranges in length from 2.5 to 5.5 millimetres (0.098 to 0.217 in). Being within the family Crabronidae, Microstigmus has a thread like waist connected between the thorax and abdomen. Unlike other Hymenoptera, the head and thorax (mesosoma) lack branched or plumose hairs. The wasps also have their posterior metatarsus modified into a cleaning mechanism. Many of the different species in this family have varying color schemes that serve to warn predators (some have venomous stings) or to provide camouflage.


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