Have you ever had a tiny animal buzz by your head, tickle the back of your neck, or crawl out of your shoe? Well, it may have been one of the 900,000 different species of insects! Many people turn away in disgust at the sight of various bugs and insects. Unfortunately, they may not realize that they are giving the cold shoulder to some of the most fascinating creatures on the planet. This article has the buzz on the five most interesting insects in North America!
#5: Blister Beetles
A very interesting insect is the blister beetle! The name “blister beetle” describes a family of 7,500 species of beetles that exist worldwide! These beetles earn their name from their interesting anti-predator behavior. When a blister beetle feels threatened, it can secrete a blistering agent called cantharidin on its attacker. This chemical can cause irritation and the formation of blisters across the skin.
Blister beetles have many other interesting defense adaptations. Many species of blister beetle have vibrant coloration. This deters predators because bright colors are associated with poisonous or venomous animals. Bright colors in animals advertising toxicity is known as aposematism. Blister beetles are toxic to eat and can be lethal. These beetles often infest hay and grasses used for animal feed and can be harmful to the livestock.
Another interesting characteristic of the blister beetle is its development. These beetles are hypermetamorphic which means they go through multiple different larval stages, also known as instars. It is common for insects to have multiple larval stages during metamorphosis, however, hypermetamorphic species have instars that are functionally and morphologically distinct. Hypermetamorphic species are collectively very interesting insects!
#4: Hercules Beetles
The Hercules beetle, a species of rhinoceros beetle, is an interesting insect that inhabits North America, Central America, and South America. This beetle lives primarily in Central America but has expanded north into Mexico. The Hercules beetle is not only one of the largest flying insects in the word but is also the largest out of all 400,000 species of beetles! Male Hercules beetles have a long horn that can give them a total body length up to 7 inches!
Hercules beetle mating behavior is incredibly interesting. Like many animal species, male Hercules beetles compete for mates. This competition is responsible for the sexual dimorphism in the species, especially the large male horn. Sexual dimorphism is when the male and female of a species have drastically different physical characteristics due to sexual selection. The male beetles use their horns to pin and throw their opponent when battling for a mate. The battle can cause serious physical injury because of the beetle’s outstanding strength- they can lift as much as 850 times their body weight! Injury is worth it, however, because the winning male gains access to the female mate.
Hercules beetles are also a crucial factor to their ecosystem. They typically inhabit rainforests and have an important role especially when in their larval stage. In this stage of their development, they feed on decaying wood. By doing this, they are key in the process of plant decomposition and nutrient cycling. The Hercules beetle’s conservation status is unknown because of its complex distribution. Population fluctuations also create difficulty for scientists studying these interesting insects and generate an accurate count.
The next group of most interesting insects is the taxonomic family Formicidae: ants! Ants exist on all continents except Antarctica! There are 13, 800 species of ants officially recognized including 2,500 in Africa, 2,162 in the Neotropics, and 2,080 species in Asia. Ants, despite how common they are, are incredibly fascinating creatures! They have complex social structures and behaviors, a variety of mutualistic relationships with other animal and plant species, unique physical adaptations, and an important ecological role.
Physically, ants are particularly unique in their body plan and relative strength. Interestingly, an ant’s heart is at the tail-end of its segmented body. Unlike other insects, ants have bent, jointed antennae, and metapleural glands. These special glands secrete an antibiotic agent that prevents bacteria and fungal spores from growing on the ant’s exoskeleton. Some ants are venomous or poisonous. The Maricopa carpenter ant, for example, has the most toxic insect venom in the world.
Many species of ants also exemplify polymorphism. This is when there are different physical forms, or morphs, within one species. Polymorphism in many species of ants relates to the ant’s position and role in a social caste system. The size-classes of worker ants are classified as minor, median, and major with increasing body size. Some colonies also have drone ants and queens. In the species Carebara diversa, or East Indian harvesting ant, the difference in dry weight between the largest and smallest worker ants is 500-fold! Divisions of labor allow ants to collectively solve complex issues like a society and work as one entity called a “superorganism”.
Worker ants in many species are unable to mate because of chromosomal differences. There is one or more fertile queen in each colony that mates with male drones, some of which are fertile. In other ant species, non-queen females can also reproduce asexually. Evolutionary biologists have studied animal colonies where there is only one reproductive female whose reproductive success is prioritized over others. Typically, in biology it is found that plants or animals are selfish and will adapt to improve their own reproductive success; however, in some situations it is more beneficial to help related individuals instead.
In a colony, individuals are closely related and share much of the same genetic material. If an individual is able to help enough of their relatives reproduce so that more shared genes are passed on to the next generation than if they had their own offspring, then it is advantageous to sacrifice one’s own reproduction to promote a relative’s. This is an example of altruistic kin selection- which is acting to increase the reproductive success of a relative at the expense of oneself.
Different species of ants also have mutualistic relationships with other animals and plants! A mutualistic relationship is when two or more different species mutually benefit each other. An example in ants is the relationship between leafcutter ants and fungi. This mutualistic relationship in particular is obligatory and is required for the survival of both the ants and the fungi. The ants tend to the fungus by feeding it plant material and ridding it of mold and pests. If the plant material they bring the fungus is toxic or harmful, the fungus can use chemical signalling to communicate with the ants to not to bring that plant again. The fungus must have the ants bringing it resources to survive and the ants must harvest the fungus to feed their larvae.
Ecologically, ants have a massive role. Not only do they help other species via mutualistic relationships, but they also act as an indicator species. Because ants are so widespread and so influential on other wildlife, their population’s wellbeing can be monitored to indicate the qualitative health of their entire ecosystem. This can reveal information about how pollution, an invasive species, climate change, natural disasters, or a number of other factors have impacted the environment. The conservation status of ants collectively cannot be determined but most species are evaluated as least concern.
#2: Periodical Cicadas
One of the most interesting insects widespread in North America is the periodical cicada. Periodical cicadas are cicadas belonging to the genus Magicicada. These insects have an incredibly unique life cycle that generates questions still left to be answered by entomologists. Periodical cicadas are found in the midwestern, eastern, and southern United States and exist in 15 distinct broods that emerge in cycles of 13 or 17-year periods. They spend 99.5% of their lives underground! Recently, in April of 2021, Brood X (also known as the Great Eastern Brood) emerged after 17 years underground!
What makes periodical cicadas so fascinating is that when a brood does emerge after 13 or 17 years, they emerge simultaneously in huge numbers. The 2021 Brood X emergence included as many as 1.5 million cicadas per acre in parts of Indiana, Pennsylvania, Maryland, Washington D.C, New Jersey, Delaware, Tennessee, and Virginia. Juvenile cicadas, called nymphs, spend years of development underground and emerge during their 5th larval stage. During this stage, the cicadas emerge from the ground and find a high place such as a tree trunk or telephone pole to undergo their final molt. Periodical cicadas are only adults for a couple of weeks before dying, so their sole focus is reproducing. You may have heard the incredibly loud cicadas singing their mating songs before!
Scientists have theories as to why and how periodical cicadas time their emergence so precisely in set intervals. One theory for why they emerge in periods of 13 or 17 years, beyond simply accommodating a long developmental stage, is because these are prime numbers. Many insects that reproduce and emerge annually, or in some other predictable time cycles, are heavily predated on. Predators can learn when a food source is available and maximize their efficiency in obtaining that resource, so periodical cicadas emerge at unintuitive periods to deter predation.
Additionally, emerging in large numbers has an evolutionary advantage. This principle is predator satiation- a prey population appears in large numbers to decrease the likelihood of any one individual being singly vulnerable. For example, when playing tag, it is harder to chase down and tag your best friend when you are playing with 100 people than if you are playing with just two people.
The most interesting insects in North America are bumblebees! Bees have incredibly fascinating behavior, social structures, reproductive biology, and a massive ecological role as a keystone species. Bees are present on every continent with the exception of Antarctica and are critical to every ecosystem they inhabit. These widespread insects are also present in human culture in the form of art, poems, and other writings. Rock drawings of bees in Spain date back to 15,000 BCE! It is very important to learn about these interesting insects because of their impact on the environment and on human culture.
Similar to ants, bees live in colonies with complex social structures. They exhibit eusociality which is the highest classification of sociality in animals. This classification requires that there is cooperative brood care, overlapping generations within a colony of adults, and division of labor in reproductive and nonreproductive groups. In a beehive, there is one fertile queen, many non-reproducing female worker bees, and several fertile male drones. Polymorphism exists that differentiates workers, drones, and queens in physiological ways. Queen bees, for example, as the only reproductive female, must reproduce in high numbers. Queens have a special organ that stores sperm so when the queen goes on her first and only “nuptial flight” around the hive to collect sperm, she can store it to be used for the duration of her reproductive life.
Bees therefore also exemplify altruistic kin selection in that genetically related individuals sacrifice their own reproduction to better ensure their relative’s success. As the female worker bees are all children of the queen and sisters to each other, their reproductive fitness is higher when they support the queen rather than reproducing themselves.
A very interesting behavior long studied by scientists is bee dancing. When a worker bee finds a food source, they return to their hive and perform a dance to communicate where the food source is. There are two forms of dancing: the round dance and the waggle dance. The round dance is when the bee moves in circles, which communicates that there is a food source within 15-100 meters of the hive.
The waggle dance communicates both distance and direction. The bee moves in a figure eight and waggles its rear end down the middle of the two circles. The length of the waggle translates to how far the food source is with one second of waggling equalling 1 kilometer away from the hive. The angle of the dance relative to the hive communicates direction: waggling straight up indicates the food source is towards the sun and down the hive means away from the sun. Using a chart of where the sun is in the sky at different times of day, we can interpret the bee dances and understand what they are communicating to their hive-mates.
Bees are an example of a keystone species. In architecture, the keystone is the piece at the top of an arch that if removed will cause the arch to collapse. A keystone species is one that if removed from an ecosystem, that ecosystem risks collapsing. Keystone species hold a role that has environmental consequences disproportionate to their population size. Honeybees have this classification because of their role as pollinators. Bees require pollen and nectar from plants, plants require pollinators to reproduce, herbivores require plants, and carnivores require herbivores. If bees are missing from this web of interspecies interactions, their ecosystem would crumble from the bottom up. Some honeybee species have the conservation status of least concern, but some species are listed as vulnerable and critically endangered.
The photo featured at the top of this post is © feathercollector/Shutterstock.com
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