Although these brightly-coloured insects look like bees or wasps, they are in fact true flies and do not sting.
Hoverfly populations are encouraged by gardeners as their larvae feed on insects like aphids, thrips, and leaf hoppers, which are harmful to plants.
Batesian mimicry is a survival tactic employed by a relatively harmless species to escape potential predators by exhibiting the appearance of a harmful species. The hoverfly employs this tactic to look like a wasp, bee, or even hornet, and is often mistaken by people and predators alike. Being a true fly, it doesn't bite or sting.
Hoverflies, commonly known as flower flies, belong to the Syrphidae family, and hence, they are often also called syrphid flies. They get their common names from their habit of hovering over flowers in order to feed on nectar. Due to their diet of nectar, they also act as pollinators. According to the Encyclopedia Britannica, there are close to about 6,000 species of these flies. They are commonly found throughout the world on all continents except Antarctica.
How to identify a hoverfly?
The easiest way to identify a hoverfly is via its characteristic hovering, as bees and wasps do not hover much. Other ways to differentiate them involve close physical examination of the fly body. The bristles on the dorsal thorax are short and soft, and the antennae on the head are shorter than those of wasps. These flies are true flies belonging to the order Diptera, and hence have only one pair of wings and not two pairs as in the case of bees and wasps.
The wings of the flower flies also show the presence of a longitudinal "vena spuria", which is a false vein that ends abruptly along the wing. The wing also has two cross veins: upper outer and lower outer cross veins.
What do they look like?
Eyes of a Male Hoverfly
Males have larger eyes that are placed close together such that they form a triangular structure.
Eyes of a Female Hoverfly
The eyes of the females, on the other hand, are slightly smaller and placed apart.
While the overall appearance is similar to other arthropod insects, such as bees and wasps, these flies exhibit a vast range of size and appearance―some are small and elongated, while others are large and hairy. They all have similar characteristic bright yellow markings in the form of spots, stripes, and bands. They have short and stubby antennae and have large, round compound eyes. The eyes are larger in case of males, and help them recognize females more accurately. The eyes can also be used to differentiate/identify the sex of these flies.
Where do they live?
They have a variety of habitats ranging from woodlands to urban areas. Hoverflies thrive in almost any environment as long as the vegetation is plentiful enough to sustain all its growing stages. They can establish populations in all climates except the desert and tundra regions.
What do they eat?
The hoverfly larvae feed on aphid and other soft-bodied insects such as thrips, leafhoppers, etc. The immature and adult flies feed mostly on the nectar and pollen from flowers, and honeydew from aphids. Some species also consume dead and decaying matter.
How do they reproduce?
The hoverfly's lifespan is approximately one month, and their life cycle takes place in four stages: egg, larva, pupa, and adult (imago). The period of their life cycle varies with the seasons. It spans three weeks in summer, whereas in winter, it spans a period of nine weeks.
An abundance of pollen as a food source is a prerequisite for the mating of flower flies. Mature adults mate in early summer. The males mature faster than the females. This ensures successful reproduction. Mating may take place while flying or terrestrially resting on foliage.
A female hoverfly laying eggs
A female can lay up to 100 eggs during the course of their life. Females lay the fertilized eggs on plant shoots and leaves where they will have easy access to prey. The eggs are elongated ovals in shape and are whitish in color.
When the eggs hatch, the larvae emerge and start feeding on the plant leaves and aphid populations. They also feed on other small, soft insects. The larvae consume hundreds of aphids in this stage. The larvae are legless and maggot-like.
Pupae are oblong and pear-shaped. Their color changes gradually from green to that of the adult hoverfly. Pupation helps them metamorphose into imagoes. The imagoes emerge from the pupae as young hoverflies. They feed on nectar, pollen, and honeydew from aphids and mature into adult flies. In a year, 3 to 7 generations of these syrphid flies may be produced.
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This site provides links to random videos hosted at YouTube, with the emphasis on random.
The original idea for this site actually stemmed from another idea to provide a way of benchmarking the popularity of a video against the general population of YouTube videos. There are probably sites that do this by now, but there wasn’t when we started out. Anyway, in order to figure out how popular any one video is, you need a pretty large sample of videos to rank it against. The challenge is that the sample needs to be very random in order to properly rank a video and YouTube doesn’t appear to provide a way to obtain large numbers of random video IDs.
Alternative random YouTube videos generator: YouTuBeRandom
Even if you search on YouTube for a random string, the set of results that will be returned will still be based on popularity, so if you’re using this approach to build up your sample, you’re already in trouble. It turns out there is a multitude of ways in which the YouTube search function makes it very difficult to retrieve truly random results.
So how can we provide truly random links to YouTube videos? It turns out that the YouTube programming interface (API) provides additional functions that allow the discovery of videos which, with the right approach, are much more random. Using a number of tricks, combined some subtle manipulation of the space-time fabric, we have managed to create a process that yields something very close to 100% random links to YouTube videos.
YouTube is an American video-sharing website headquartered in San Bruno, California. YouTube allows users to upload, view, rate, share, add to playlists, report, comment on videos, and subscribe to other users. It offers a wide variety of user-generated and corporate media videos. Available content includes video clips, TV show clips, music videos, short and documentary films, audio recordings, movie trailers, live streams, and other content such as video blogging, short original videos, and educational videos. Most content on YouTube is uploaded by individuals, but media corporations including CBS, the BBC, Vevo, and Hulu offer some of their material via YouTube as part of the YouTube partnership program. Unregistered users can only watch videos on the site, while registered users are permitted to upload an unlimited number of videos and add comments to videos. Videos deemed potentially inappropriate are available only to registered users affirming themselves to be at least 18 years old.
YouTube and selected creators earn advertising revenue from Google AdSense, a program which targets ads according to site content and audience. The vast majority of its videos are free to view, but there are exceptions, including subscription-based premium channels, film rentals, as well as YouTube Music and YouTube Premium, subscription services respectively offering premium and ad-free music streaming, and ad-free access to all content, including exclusive content commissioned from notable personalities. As of February 2017, there were more than 400 hours of content uploaded to YouTube each minute, and one billion hours of content being watched on YouTube every day. As of August 2018, the website is ranked as the second-most popular site in the world, according to Alexa Internet, just behind Google. As of May 2019, more than 500 hours of video content are uploaded to YouTube every minute.
YouTube has faced criticism over aspects of its operations, including its handling of copyrighted content contained within uploaded videos, its recommendation algorithms perpetuating videos that promote conspiracy theories and falsehoods, hosting videos ostensibly targeting children but containing violent and/or sexually suggestive content involving popular characters, videos of minors attracting pedophilic activities in their comment sections, and fluctuating policies on the types of content that is eligible to be monetized with advertising.