Yellow meadow ant

Lasius flavus

The yellow meadow ant, is one of the most common ants in Central Europe, and it also occurs in Asia and North Africa, but populations in North America are a different, related species (Lasius brevicornis).
Bridal flight / Nuptial flight of the Yellow meadow ant, Heesch, Netherlands (hard to see, but this photo features both the female workers (tiny, orange) and the winged males (large, black))

Today I was lucky to discover a "Bridal Flight" in the small lawn of our backyard.

This particular species lives entirely below ground, where they milk aphids that feed on the roots of grass and other plants for honeydew. This ant species takes this symbiotic relation quite far: they create large underground chambers where said aphids can feed in peace, uninterrupted. They even hatch the eggs of the aphids to secure a new generation of "cows" and then transport them to the feeding chambers.

These ants don't like direct sunlight, yet do need some of its heat for their nest. In a natural habitat with tall grass, their nest will look like a bump above ground. In a situation with short grass (mowed lawn), the entire nest is below ground, and you're unlikely to know it even exists...unless you're lucky to witness this event. I found two nests on the same lawn, both having their bridal flight.

Most of the colony consists of female workers, which are small (3-5mm) and orange. They have a very juvenile or albino appearance, yet are adults. Unusual for ant workers, they are not uniform in size. Small workers take care of the queen whilst big workers handle food logistics.

The female workers make the call on timing the bridal flight. The decision is based on conditions, for many species it concerns the first hot and moist day after a cooler period in summer. Amazingly, timing is so reliable that this event is synchronized. Every independent nest will fly on the same day. Across the country, or territory with similar conditions.

The decision involves the physical process of female workers enlarging the nest opening, otherwise the queen can't get out. Next, ants are chased out of the opening.

Which sets the bridal stage. It largely consists of male ants, which only exist for a few weeks of the year, and are large, winged, and black. They come out by the hundreds or thousands. They are crash pilots, as they've never before used their wings. But they must, in an effort to reach the queen.

The queen flies as high as possible, as it favors to mate with a male from another nest, and not one of her own brothers. Yet the brothers try, climbing, crashing, pushing competitors down, all to reach the price. The lucky male to succeed, will deliver enough seed for the queen to lay eggs for life. 

And then all males die.

The queen may return to the nest for expansion, or create a new nest elsewhere. They'll try to find a safe place for the winter and start the colony the next spring. Some nests may be founded by multiple queens, yet only one egg-laying queen will remain, the others are killed by the workers.

Some people unaware of these nests freak out by this sudden unexpected explosion of ants, and may try to exterminate them. Don't! This is a critical day in their life cycle, let it happen uninterrupted. All males die and will be picked up by birds. Female workers retreat to the nest. The scene cleans itself up. Therefore, enjoy it. It's a marvel.

https://www.jungledragon.com/image/119776/bridal_flight_of_the_yellow_meadow_ant_-_nest_heesch_netherlands.html
https://www.jungledragon.com/image/119775/bridal_flight_of_the_yellow_meadow_ant_heesch_netherlands.html
https://www.jungledragon.com/image/119779/bridal_flight_of_the_yellow_meadow_ant_-_competition_heesch_netherlands.html Heesch,Lasius flavus,Yellow meadow ant

Appearance

The queen is 7–9 mm long, males 3–4 mm and workers 2–4 mm. Their colour varies from yellow to brown, with queen and males being slightly more darkly colored.
Yellow Meadow Ant These ants were moving their eggs around the nest on the grass after it was accidentally disturbed. Lasius flavus,Yellow meadow ant

Behavior

The yellow meadow ant feeds on the honeydew from root aphids, which they breed in their nests. During winter, the aphids themselves are sometimes eaten. As a consequence of their feeding habits, the species only occasionally forages outside the nest. Evidence of their underground lives is their lack of pigmentation and the smaller size of their eyes, compared to closely related species like the black garden ant. They are a timid species and will often simply barricade their tunnels to fight off invaders.
Lasius flavus  Ants,Arthropods,Geotagged,Germany,Insects,Lasius flavus,Macro,Yellow meadow ant

Habitat

The species lives primarily underground in meadows and very commonly, lawns. The nests are often completely overgrown by grass, however, often their presence is betrayed by small mounds of loose soil material between the grass stalks. They will also nest under large rocks or concrete slabs. Lawn nesting will eventually become obvious as the aphids clear sections of grass or portions of gardens.

References:

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Taxonomy
KingdomAnimalia
DivisionArthropoda
ClassInsecta
OrderHymenoptera
FamilyFormicidae
GenusLasius
SpeciesL. flavus