Insect Flight Research Articles

Metabolic gatekeepers: Dynamic roles of sugar transporters in insect metabolism and physiology.

Sugars play multiple critical roles in insects, serving as energy sources, carbon skeletons, osmolytes and signalling molecules. The transport of sugars from source to sink via membrane proteins is essential for the uptake, distribution and utilization of sugars across various tissues. Sugar supply and distribution are crucial for insect development, flight, diapause and reproduction. Insect sugar transporters (STs) share significant structural and functional similarities with those in mammals and other higher eukaryotes. However, they exhibit unique characteristics, including differential regulation, substrate selectivity and kinetics. Here, we have discussed structural diversity, evolutionary trends, expression dynamics, mechanisms of action and functional significance of insect STs. The sequence and structural diversity of insect STs, highlighted by the analysis of conserved domains and evolutionary patterns, underpins their functional differentiation and divergence. The review emphasizes the importance of STs in insect metabolism, physiology and stress tolerance. It also discusses how variations in transporter regulation, expression, selectivity and activity contribute to functional differences. Furthermore, we have underlined the potential and necessity of studying these mechanisms and roles to gain a deeper understanding of insect glycobiology. Understanding the regulation and function of sugar transporters is vital for comprehending insect metabolism and physiological potential. This review provides valuable insights into the diverse functionalities of insect STs and their significant roles in metabolism and physiology.

Studies on Lygus pratensis' (Hemiptera: Miridae) Flight Ability.

Lygus pratensis (Linnaeus) is an important agricultural pest with a strong ability to move and spread between hosts. However, L. pratensis' flight potential and factors affecting its flight ability are unclear. We used the insect flight information system (flight mill) to determine the effects of temperature, humidity, age, sex, and mating on L. pratensis' flight ability in an artificial climate chamber. Temperature and relative humidity significantly affected L. pratensis' flight ability; however, low and high temperature, as well as low humidity, were unsuitable, and the optimal flight environment was 20-28 °C and 60-75% RH. Lygus pratensis' flying ability initially increased and then decreased with age and was highest at 10 days old (flight rate: 71.43%; total flight distance: 18.63 ± 1.89 km; total flight time: 6.84 ± 0.60 h). At 15 days old, flight speed was the highest (3.36 ± 0.18 km h-1). Sex had little effect on L. pratensis' flying ability; it was marginally stronger for females than males, but the difference was insignificant. Mating increased female flying ability but decreased that of males, but the difference was insignificant. Overall, L. pratensis had strong flight dispersal ability, was largely unaffected by sex and mating, and optimal flight conditions were mild temperature and humidity. This knowledge provides a scientific basis for L. pratensis outbreak prediction, prevention, and control.

Determination of the Flight Capacity of Tuta absoluta (Lepidoptera: Gelechiidae)1

Abstract Since invading Xinjiang, China in 2017, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), commonly known as the tomato leafminer or the South American tomato pinworm moth, has continuously expanded its scope of devastation. Because flight is a major means by which insects disperse, an insect flight mill was employed to elucidate the physiological boundaries and basic parameters of T. absoluta flight biology. The system was used to measure the average flight distance, flight time, and flight speed of adult male and female T. absoluta of different ages, including 5-d-old (post emergence) adults in different mating states that had received supplementary nutrition (5% honey water). Tests of 12 h of continuous suspension in a flight mill showed that 4 through 7-d-old adults had strong flying ability, but 5-d-old adults were the strongest flyers. The mean (±SEM) flight distance, flight time, and flight speed of 5-d-old females were 1.805 ± 0.040 km, 1.467 ± 0.036 h, and 1.231 ± 0.226 km/h, respectively. The mean (±SEM) flight distance, time, and speed of 5-d-old males were 1.627 ± 0.363 km, 1.950 ± 0.056 h, and 0.834 ± 0.202 km/h, indicating significant differences in flight ability between male and female adults. After feeding on 5% honey water, the flight ability of 5-d-old T. absoluta improved significantly compared with the control. The distance, time, and flight speed of honey-water fed 5-d-old virgin females increased by 16.73%, 8.32%, and 8.37%, compared with the control (fed honey-free water). The flight distance, time, and speed of 5-d-old males increased by 7.87%, 0.56%, and 7.07% respectively, compared with the control. After mating, the distance, time, and flight speed of 5-d-old female adults increased by 11.91%, 0.48%, and 11.29% compared with virgin female adults. However, after 5-d-old males mated, their corresponding flight ability decreased by 11.13%, 3.34%, and 7.34%, compared with virgin male adults. In summary, sex, supplementary nutrition, and mating status all have a significant impact on the flight ability of T. absoluta.

Automated classification of mixed populations of Aedes aegypti and Culex quinquefasciatus mosquitoes under field conditions

BackgroundThe recent rise in the transmission of mosquito-borne diseases such as dengue virus (DENV), Zika (ZIKV), chikungunya (CHIKV), Oropouche (OROV), and West Nile (WNV) is a major concern for public health managers worldwide. Emerging technologies for automated remote mosquito classification can be supplemented to improve surveillance systems and provide valuable information regarding mosquito vector catches in real time.MethodsWe coupled an optical sensor to the entrance of a standard mosquito suction trap (BG-Mosquitaire) to record 9151 insect flights in two Brazilian cities: Rio de Janeiro and Brasilia. The traps and sensors remained in the field for approximately 1 year. A total of 1383 mosquito flights were recorded from the target species: Aedes aegypti and Culex quinquefasciatus. Mosquito classification was based on previous models developed and trained using European populations of Aedes albopictus and Culex pipiens.ResultsThe VECTRACK sensor was able to discriminate the target mosquitoes (Aedes and Culex genera) from non-target insects with an accuracy of 99.8%. Considering only mosquito vectors, the classification between Aedes and Culex achieved an accuracy of 93.7%. The sex classification worked better for Cx. quinquefasciatus (accuracy: 95%; specificity: 95.3%) than for Ae. aegypti (accuracy: 92.1%; specificity: 88.4%).ConclusionsThe data reported herein show high accuracy, sensitivity, specificity and precision of an automated optical sensor in classifying target mosquito species, genus and sex. Similar results were obtained in two different Brazilian cities, suggesting high reliability of our findings. Surprisingly, the model developed for European populations of Ae. albopictus worked well for Brazilian Ae. aegypti populations, and the model developed and trained for Cx. pipiens was able to classify Brazilian Cx. quinquefasciatus populations. Our findings suggest this optical sensor can be integrated into mosquito surveillance methods and generate accurate automatic real-time monitoring of medically relevant mosquito species.Graphical

You are what you eat - The influence of polyphagic and monophagic diet on the flight performance of bees.

Movement performance of insects is an important measure of physiological fitness and is likely affected by novel stressors associated with global change. Reduced fitness can lead to smaller foraging areas and thus to decreasing abundance, diversity and nutritional quality, which could weaken insect populations and contribute to global insect decline. Here, we combined two different methods: An experimental semi-field design applying treatments in outdoor flight cages and a follow-up experiment conducted in the laboratory, in which different parameters of movement performance, such as (a) velocity, (b) duration and (c) distance of an insect's flight can be quantified. We kept colonies of the bumblebee Bombus terrestris under contrasting nutritional conditions and measured treatment effects on the movement performance of individuals. Monophagously fed bumblebees showed reduced movement performance than polyphagously fed bumblebees. In particular, they stopped more frequently during flight, flew shorter distances and showed less often flight duration of 20 min. Our results suggest that nutritional deficiency due to a monophagic diet leads to reduced flight performance, which can have dramatic negative consequences for bees. Reduced flight performance may result in decreased availability of host plants, which may negatively affect stress resistance of bees and brood provisioning, facilitating extinction of insects. Although food of great nutritional value is an important compensator for the negative effects of different novel stressor, such as pesticides, it is not much known how to compensate for the effects of nutritional stress, especially in landscapes dominated by monocultures. However, our experimental approach with semi-field and laboratory components has high potential for further studies investigating the impact of different stressors on the physiological fitness of insects but also body mass, or reproductive success and to find factors that may mitigate or even overcome the negative effect of stressors on insects.

Drag force on an accelerating flat plate at low Reynolds numbers

The accelerating flat plate is a useful model for studying the drag-based flapping flight (where drag is used to provide the weight-supporting force or thrust). Previous studies have mainly focused on the high Reynolds number (Re) regime pertaining to the flight of relatively large insects and birds. In this study, we numerically investigate the unsteady drag and flows of a uniformly accelerating flat plate at low Re that is typical of miniature insect flight (Re = 10–40). The following is shown. Unlike high-Re cases where the acceleration effect on drag is insensitive to Re, at low Re, the effect exhibits a strong dependence on Re: As Re decreases below 100, the acceleration effect increases rapidly, becoming 33%–56% greater than that of high-Re cases in the Re range of 10–40, before gradually decreasing. A simple model that consists of the quasi-steady, added-mass, and history force terms is proposed for drag at low Re. The scalings of the quasi-steady and added-mass force terms are well known; we find that the history force term scales approximately with the square root of the acceleration and velocity. The above result that relatively large drag is produced by the accelerating wing at Re = 10–40 is especially interesting and might explain why miniature insects fly in this Re range.

Aerodynamic Effects of Time-Varying Corrugations on Dragonfly Wings in Flapping Flight.

The aerodynamic effects of wing corrugation on insect flight have received widespread attention. However, there has hardly been any specific focus on dynamic changes to corrugation angle in the models. The flexible vein joints containing resilin in the wings of dragonflies and damselflies enable the longitudinal veins to rotate and thereby change the corrugation angles throughout flapping cycles. Therefore, a two-dimensional corrugated airfoil with time-varying corrugation angles is proposed and the aerodynamic performance is evaluated in terms of aerodynamic force, power and efficiency. The results indicate that the airfoil with time-varying corrugations outperforms the rigid one in terms of enhancing thrust and reducing power consumption. The aerodynamic performance of time-varying corrugated airfoils is optimal when the angle varies in a specific range, and an excessively large angle variation may have negative effects. In addition, excessive height or a negative leading edge of the corrugation can lead to a reduction in the thrust. A design concept for the 2D airfoil with time-varying corrugations is provided and the findings are of significance for enhancing the aerodynamic performance of biomimetic flexible flapping-wing vehicles.

Insect Flight: State of the Field and Future Directions.

The evolution of flight in an early winged insect ancestral lineage is recognized as a key adaptation explaining the unparalleled success and diversification of insects. Subsequent transitions and modifications to flight machinery, including secondary reductions and losses, also play a central role in shaping the impacts of insects on broadscale geographic and ecological processes and patterns in the present and future. Given the importance of insect flight, there has been a centuries-long history of research and debate on the evolutionary origins and biological mechanisms of flight. Here, we revisit this history from an interdisciplinary perspective, discussing recent discoveries regarding the developmental origins, physiology, biomechanics, and neurobiology and sensory control of flight in a diverse set of insect models. We also identify major outstanding questions yet to be addressed and provide recommendations for overcoming current methodological challenges faced when studying insect flight, which will allow the field to continue to move forward in new and exciting directions. By integrating mechanistic work into ecological and evolutionary contexts, we hope that this synthesis promotes and stimulates new interdisciplinary research efforts necessary to close the many existing gaps about the causes and consequences of insect flight evolution.

Generating controlled gust perturbations using vortex rings.

To understand the locomotory mechanisms of flying and swimming animals, it is often necessary to develop assays that enable us to measure their responses to external gust perturbations. Typically, such measurements have been carried out using a variety of gusts which are difficult to control or characterize owing to their inherently turbulent nature. Here, we present a method of generating discrete gusts under controlled laboratory conditions in the form of a vortex rings which are well-characterized and highly controllable. We also provide the theoretical guidelines underlying the design of gust generators for specific applications. As a case study, we tested the efficacy of this method to study the flight response of freely-flying soldier flies Hermetia illucens. The vortex ring based method can be used to generate controlled gusts to study diverse phenomena ranging from a natural flight in insects to the artificial flight of insect-sized drones and micro-aerial vehicles.

Altering developmental oxygen exposure influences thermoregulation and flight performance of Manduca sexta.

Endothermic, flying insects are capable of some of the highest recorded metabolic rates. This high aerobic demand is made possible by the insect's tracheal system, which supplies the flight muscles with oxygen. Many studies focus on metabolic responses to acute changes in oxygen to test the limits of the insect flight metabolic system, with some flying insects exhibiting oxygen limitation in flight metabolism. These acute studies do not account for possible changes induced by developmental phenotypic plasticity in response to chronic changes in oxygen levels. The endothermic moth Manduca sexta is a model organism that is easy to raise and exhibits a high thorax temperature during flight (∼40°C). In this study, we examined the effects of developmental oxygen exposure during the larval, pupal and adult stages on the adult moth's aerobic performance. We measured flight critical oxygen partial pressure (Pcrit-), thorax temperature and thermoregulating metabolic rate to understand the extent of developmental plasticity as well as effects of developmental oxygen levels on endothermic capacity. We found that developing in hypoxia (10% oxygen) decreased thermoregulating thorax temperature when compared with moths raised in normoxia or hyperoxia (30% oxygen), when moths were warming up in atmospheres with 21-30% oxygen. In addition, moths raised in hypoxia had lower critical oxygen levels when flying. These results suggest that chronic developmental exposure to hypoxia affects the adult metabolic phenotype and potentially has implications for thermoregulatory and flight behavior.

Pollinator activity and flowering in agricultural weeds in Sweden.

The extent to which weeds in arable land are useful to pollinators depends in part on the temporal pattern of flowering and insect flight activity. We compiled citizen science data on 54 bees and hoverflies typical of agricultural areas in southern Sweden, as well as 24 flowering weed species classified as pollinator-friendly in the sense that they provide nectar and/or pollen to pollinators. The flight periods of the bees and hoverflies varied greatly, but there were also some consistent differences between the four groups studied. The first group to fly were the early flying solitary bees (7 species), followed by the social bees (18 species). In contrast, other solitary bees (11 species) and hoverflies (22 species) flew later in the summer. Solitary bees had the shortest flight periods, while social bees and hoverflies had longer flight periods. Flowering of weed species also varied greatly between species, with weeds classified as winter annuals (e.g., germinating in autumn) starting early together with germination generalists (species that can germinate in both autumn and spring). Summer annuals (spring germinators) and perennials started flowering about a month later. Germination generalists had a much longer flowering period than the others. Weekly pollinator records were in most cases significantly explained by weed records. Apart from early flying solitary bees, all models showed strong positive relationships. The overall best explanatory variable was the total number of weeds, with a weight assigned to each species based on its potential as a nectar/pollen source. This suggests that agricultural weeds in Sweden provide a continuous potential supply of nectar and pollen throughout the flight season of most pollinators.

Biomechanics of Insect Flight Stability and Perturbation Response.

Insects must fly in highly variable natural environments filled with gusts, vortices, and other transient aerodynamic phenomena that challenge flight stability. Furthermore, the aerodynamic forces that support insect flight are produced from rapidly oscillating wings of time-varying orientation and configuration. The instantaneous flight forces produced by these wings are large relative to the average forces supporting body weight. The magnitude of these forces and their time-varying direction add another challenge to flight stability, because even proportionally small asymmetries in timing or magnitude between the left and right wings may be sufficient to produce large changes in body orientation. However, these same large-magnitude oscillating forces also offer an opportunity for unexpected flight stability through nonlinear interactions between body orientation, body oscillation in response to time-varying inertial and aerodynamic forces, and the oscillating wings themselves. Understanding the emergent stability properties of flying insects is a crucial step toward understanding the requirements for evolution of flapping flight and decoding the role of sensory feedback in flight control. Here, we provide a brief review of insect flight stability, with some emphasis on stability effects brought about by oscillating wings, and present some preliminary experimental data probing some aspects of flight stability in free-flying insects.

Induced Power Scaling Alone Cannot Explain Griffenfly Gigantism.

Paleozoic skies were ruled by extinct odonatopteran insects called "griffenflies," some with wingspans 3 times that of the largest extant dragonflies and 10 times that of common extant dragonflies. Previous studies suggested that flight was possible for larger fliers because of higher atmospheric oxygen levels, which would have increased air density. We use actuator disk theory to evaluate this hypothesis. Actuator disk theory gives similar estimates of induced power as have been estimated for micro-air vehicles based on insect flight. We calculate that for a given mass of griffenfly, and assuming isometry, a higher density atmosphere would only have reduced the induced power required to hover by 11%, which would have supported a flyer 3% larger in linear dimensions. Steady-level forward flight would have further reduced induced power but could only account for a flier 5% larger in linear dimensions. Further accounting for the higher power available due to high-oxygen air and assuming isometry, we calculate that the largest flyer hovering would have been only 1.19times longer than extant dragonflies. We also consider known allometry in dragonflies and estimated allometry in extinct griffenflies. But such allometry only increases flyer size to 1.22times longer while hovering. We also consider profile and parasite power, but both would have been higher in denser air and thus would not have enhanced the flyability of larger griffenflies. The largest meganeurid griffenflies might have adjusted flight behaviors to reduce power required. Alternatively, the scaling of flight muscle power may have been sufficient to support the power demands of large griffenflies. In literature estimates, mass-specific power output scales as mass0.24 in extant dragonflies. We need only more conservatively assume that mass-specific muscle power scales with mass0, when combined with higher oxygen concentrations and induced power reductions in higher-density air to explain griffenflies 3.4times larger than extant odonates. Experimental measurement of flight muscle power scaling in odonates is necessary to test this hypothesis.

Moth resonant mechanics are tuned to wingbeat frequency and energetic demands.

An insect's wingbeat frequency is a critical determinant of its flight performance and varies by multiple orders of magnitude across Insecta. Despite potential energetic benefits for an insect that matches its wingbeat frequency to its resonant frequency, recent work has shown that moths may operate off their resonant peak. We hypothesized that across species, wingbeat frequency scales with resonance frequency to maintain favourable energetics, but with an offset in species that use frequency modulation as a means of flight control. The moth superfamily Bombycoidea is ideal for testing this hypothesis because their wingbeat frequencies vary across species by an order of magnitude, despite similar morphology and actuation. We used materials testing, high-speed videography and a model of resonant aerodynamics to determine how components of an insect's flight apparatus (stiffness, wing inertia, muscle strain and aerodynamics) vary with wingbeat frequency. We find that the resonant frequency of a moth correlates with wingbeat frequency, but resonance curve shape (described by the Weis-Fogh number) and peak location vary within the clade in a way that corresponds to frequency-dependent biomechanical demands. Our results demonstrate that a suite of adaptations in muscle, exoskeleton and wing drive variation in resonant mechanics, reflecting potential constraints on matching wingbeat and resonant frequencies.

The Weis-Fogh Number Describes Resonant Performance Tradeoffs in Flapping Insects.

Dimensionless numbers have long been used in comparative biomechanics to quantify competing scaling relationships and connect morphology to animal performance. While common in aerodynamics, few relate the biomechanics of the organism to the forces produced on the environment during flight. We discuss the Weis-Fogh number, N, as a dimensionless number specific to flapping flight, which describes the resonant properties of an insect and resulting tradeoffs between energetics and control. Originally defined by Torkel Weis-Fogh in his seminal 1973 paper, N measures the ratio of peak inertial to aerodynamic torque generated by an insect over a wingbeat. In this perspectives piece, we define N for comparative biologists and describe its interpretations as a ratio of torques and as the width of an insect's resonance curve. We then discuss the range of N realized by insects and explain the fundamental tradeoffs between an insect's aerodynamic efficiency, stability, and responsiveness that arise as a consequence of variation in N, both across and within species. N is therefore an especially useful quantity for comparative approaches to the role of mechanics and aerodynamics in insect flight.

Temperature Dependency of Insect's Wingbeat Frequencies: An Empirical Approach to Temperature Correction.

This study examines the relationship between the wingbeat frequency of flying insects and ambient temperature, leveraging data from over 302,000 insect observations obtained using a near-infrared optical sensor during an eight-month field experiment. By measuring the wingbeat frequency as well as wing and body optical cross-sections of each insect in conjunction with the ambient temperature, we identified five clusters of insects and analyzed how their average wingbeat frequencies evolved over temperatures ranging from 10 °C to 38 °C. Our findings reveal a positive correlation between temperature and wingbeat frequency, with a more pronounced increase observed at higher wingbeat frequencies. Frequencies increased on average by 2.02 Hz/°C at 50 Hz, and up to 9.63 Hz/°C at 525 Hz, and a general model is proposed. This model offers a valuable tool for correcting wingbeat frequencies with temperature, enhancing the accuracy of insect clustering by optical and acoustic sensors. While this approach does not account for species-specific responses to temperature changes, our research provides a general insight, based on all species present during the field experiment, into the intricate dynamics of insect flight behavior in relation to environmental factors.

Clap-and-Fling Mechanism of Climbing-Flight Coccinella Septempunctata.

Previous studies on the clap-fling mechanism have predominantly focused on the initial downward and forward phases of flight in miniature insects, either during hovering or forward flight. However, this study presents the first comprehensive kinematic data of Coccinella septempunctata during climbing flight. It reveals, for the first time, that a clap-and-fling mechanism occurs during the initial upward and backward phase of the hind wings' motion. This discovery addresses the previously limited understanding of the clap-and-fling mechanism by demonstrating that, during the clap motion, the leading edges of beetle's wings come into proximity to form a figure-eight shape before rotating around their trailing edge to open into a "V" shape. By employing numerical solutions to solve Navier-Stokes (N-S) equations, we simulated both single hind wings' and double hind wings' aerodynamic conditions. Our findings demonstrate that this fling mechanism not only significantly enhances the lift coefficient by approximately 9.65% but also reduces the drag coefficient by about 1.7%, indicating an extension of the applicability range of this clap-and-fling mechanism beyond minute insect flight. Consequently, these insights into insect flight mechanics deepen our understanding of their biological characteristics and inspire advancements in robotics and biomimetics.

Temperature, not net primary productivity, drives continental-scale variation in insect flight activity.

The amount of energy available in a system constrains large-scale patterns of abundance. Here, we test the role of temperature and net primary productivity as drivers of flying insect abundance using a novel continental-scale data source: weather surveillance radar. We use the United States NEXRAD weather radar network to generate a near-daily dataset of insect flight activity across a gradient of temperature and productivity. Insect flight activity was positively correlated with mean annual temperature, explaining 38% of variation across sites. By contrast, net primary productivity did not explain additional variation. Grassland, forest and arid-xeric shrubland biomes differed in their insect flight activity, with the greatest abundance in subtropical and temperate grasslands. The relationship between insect flight abundance and temperature varied across biome types. In arid-xeric shrublands and in forest biomes the temperature-abundance relationship was indirectly (through net primary productivity) or directly (in the form of precipitation) mediated by water availability. These results suggest that temperature constraints on metabolism, development, or flight activity shape macroecological patterns in ectotherm abundance. Assessing the drivers of continental-scale patterns in insect abundance and their variation across biomes is particularly important to predict insect community response to warming conditions. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Insects as radar targets: size, form, density and permittivity

ABSTRACT To make biologically useful interpretations of the echo signals from an entomological radar (a radar designed and operated to observe insects in flight), it is necessary to relate basic properties of insects (i.e. their mass, size, and form) to their radio-wave scattering characters – e.g. their radar cross-section (RCS) and its variation with aspect or beam polarization. Measurements of RCSs of live or freshly dead specimens in laboratory rigs have played an important role in establishing such relationships, but it is desirable to develop and validate methods employing numerical computation, using electromagnetic calculation software, as a more widely applicable and generalizable alternative. In such computations, the insect is represented by a model with specified size, form, and composition; composition appears as the complex relative permittivity, with both polarizability (real) and loss (imaginary) terms. As a preliminary to investigating how adequately different types of electromagnetic model perform, we have collected and analysed morphometric data on adult, flight-capable specimens of a wide range of insect species, including many known to be migratory and to fly at heights where they would be detectable by radar. Our analyses reveal that appropriate densities for prolate-spheroid models of flying insects are in the range 0.60–0.76 g cm−3, which is about half that measured for air-free samples of the solids and liquids from which insect bodies are formed. From this, appropriate permittivities for the material filling the model are found to be in the range 7–11 (real component) and 2.0–3.5 (imaginary); again, these are much lower than measured values for pure insect-body material. These results enable construction of simple electromagnetic models of insects in which both spatial dimensions and masses are accurate. Computation of model RCSs and their aspect and polarization variations, and comparison of these with laboratory measurements, will be the topic of a follow-up validation study.

Insect Flight Energetics and the Evolution of Size, Form, and Function.

Flying insects vary greatly in body size and wing proportions, significantly impacting their flight energetics. Generally, the larger the insect, the slower its flight wingbeat frequency. However, variation in frequency is also explained by differences in wing proportions, where larger-winged insects tend to have lower frequencies. These associations affect the energy required for flight. The correlated evolution of flight form and function can be further defined using a lineage of closely related bee species varying in body mass. The decline in flight wingbeat frequency with increasing size is paralleled by the flight mass-specific metabolic rate. The specific scaling exponents observed can be predicted from the wing area allometry, where a greater increase (hyperallometry) leads to a more pronounced effect on flight energetics, and hypoallometry can lead to no change in frequency and metabolic rate across species. The metabolic properties of the flight muscles also vary with body mass and wing proportions, as observed from the activity of glycolytic enzymes and the phospholipid compositions of muscle tissue, connecting morphological differences with muscle metabolic properties. The evolutionary scaling observed across species is recapitulated within species. The static allometry observed within the bumblebee Bombus impatiens, where the wing area is proportional and isometric, affects wingbeat frequency and metabolic rate, which is predicted to decrease with an increase in size. Intraspecific variation in flight muscle tissue properties is also related to flight metabolic rate. The role of developmental processes and phenotypic plasticity in explaining intraspecific differences is central to our understanding of flight energetics. These studies provide a framework where static allometry observed within species gives rise to evolutionary allometry, connecting the evolution of size, form, and function associated with insect flight.