Glyphidops flavifrons

G. flavifrons is part of the Neriidae family of flies, which are broadly characterized by their elongated, forward-facing antennae with bristles along the top and a pedicel connecting to the middle region of the first flagellomere of the antenna. Species in this family typically display sexual dimorphism.[6] Although they have been found in multiple regions around the world, Neriidae are mainly concentrated and are most diverse in the tropics. Currently, Neriidae is accepted as one of the families in the larger Nerioidea superfamily, which also includes the diverse Micropezidae with Neriidae and Cypselosomatidae making up the two less-diverse sister taxa.[8]

Neriidae is divided into two subfamilies, Neriinae and Telostylinae, which can be distinguished by the presence of antennal sockets in the former and the lack thereof in the latter. G. flavifrons falls within the Neriinae subfamily according to phylogenetic analysis.[8]

Despite multiple methods of characterization being used in the past, the Neriidae clade was always supported by data, with many of the ancestral characteristics, such as an elongated head and top-oriented antennal bristles, remaining consistent across multiple phylogenetic trees.[8]

All species of neriids outside of the Australian-Oriental region can be traced to a single origin. Ancestral traits still present in these species are larger frontal and genal regions of the head, shorter femoral length, and the presence of notopleural bristles on the forecoxae of males.[8]

G. flavifrons are further classified into the Nerius group, which is characterized by larger female size, polished dorsal surface of the antennae, and a reduction in bristle length. Glyphidops is the most diverse Neotropical genera and cannot be further broken down into sub-genera based on analysis showing that the characteristic dense, whitish antennal pubescence was derived from a minimum of two convergence events.[8]

G. flavifrons eggs laid in situ on C. papaya and T. zebrina tree stems hatch on average 58 ± 4 hours after being laid. Eggs have a semi-cylindrical shape with a blunt posterior region measuring between 1-1.24 mm. Each egg has two longitudinally lateral hatching lines within the rear 1⁄6 of the egg body. Respiratory filaments extend from the anterior portion of the egg body and can measure up to 3.21 times its length. Before hatching, larvae move the body and lower jaw against the inner wall of the egg until they break through the posterior section.[4]

The larval stage is defined by three distinct larval instars. Total larval development time across all three instars is 10 ± 1 days, with larvae consistently presenting as worm-like with hairless, light-to-semi-transparent bodies. While in the larval stage, the head is fully retractable and has two mouth hooks protruding from the lower jaw. The thorax has well-defined pro-, meso-, and meta- sections with eight distinct abdominal sections containing small spines on all but two sections.[4]

Larvae range from 1.22 to 2.52 mm in length. This instar is characterized by bi-segmented antennae with an ovular top portion and a mandible that is slightly sclerotized, three times longer than it is wide, and containing 7-8 ventral teeth. No anterior spiracles can be observed at this stage.[4]

Larvae range from 2.95- 6.2 mm in length. Antennae are split into two antennomeres, or sections that are distally ovular. The number of teeth increases from 7-8 in the first instar to 10 teeth in the second instar. Anterior spiracles can be seen and measure as 2.5 times longer than the greatest width.[4]

Larvae range from 6-11.6 mm in length. Antennae have three antennomeres and the mandible no longer has individual teeth, but rather is completely fused into a mouth hook. The anterior spiracle is 0.8 times as wide as it is long and contains 9-11 digits.[4]

The pupa forms beneath the outer cuticle of the larvae and is 5.48-7.94 mm in length. It is reddish-brown with prominent wrinkles on two of the segments. Anterior spiracles are situated at the front of the pupa and contain 9-11 digits, all sclerotized. The puparium stage lasts 13 ± 2 days, with pupation itself lasting between 150 and 175 minutes. The adult fly emerges from a circular suture between the anterior spiracles and halfway through the abdominal sections, which completely separate as the adult emerges.[4]

Male aggression typically only occurs in the presence of a female. Lone males crossing paths while looking for a mate are most likely to ignore each other, although there is a chance one or both will display low-level aggression in the form of jerky, sudden dashes toward the other individual.[7] The majority of aggressive male behavior is observed in the presence of females. Males are known to attack copulating pairs, most often with preliminary threat tactics such as stilting or dashing toward the pair in an effort to displace the male.[7][9] Usually the battle is won by the larger male. Higher-level aggression manifests in physical contact initiated by one male lunging at one another and is resolved either when one male walks away or both males fall off the bark.[7]