Australian Cuckoo Bee

Cuckoo bees are some of the most interesting native Australian bee species. Instead of building and maintaining a nest like normal bees do, they take note from their avian counterparts. Cuckoo bees infiltrate the nest of another, closely related species and lays her eggs in it, oftentimes dooming the host's eggs in the process. This way they trick other bees to do their dirty work and raise their young. Hence why cuckoo bees are known are known as kleptoparasites.

Cuckoo bees can be detrimental to social bee species if they remain undetected. Lucky for most potential host species, these brood parasites are few and far between. Even so, the biological arms race continues. Hosts get better at detecting them and cuckoo bees get better at infiltration in a deadly game of cat and mouse.

Because of their inability to take care of their own brood, cuckoo bees have evolved to trick others into doing it for them. Since they are so dependent on their host, they have evolved a way to pick their hosts properly - they almost always infest pollen-collecting species. This way their brood uses the gathered pollen as a food source.

Alternatively, cuckoo bee larvae can also snack on the host species eggs or larvae. Either way, if things get to that point, the host rarely (if ever) survives. Which is why bee species that are frequently plagued by cuckoos develop the ability to better detect these parasites.

The female infiltrates the host's nest and makes her way to the brood chamber. She lays her eggs inside and ideally leaves undetected. The host then returns with the pollen and seals the cells. Little does she know there's a phantom menace inside.

Cuckoo bee eggs then hatch before the host eggs and begin to rapidly develop. They eat the pollen and oftentimes the larvae of the host species. Even if they don't kill them directly, the host larvae starve to death. Either way, they die so that the cuckoo bees can live.

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Even though cuckoo bees are solitary, they can also infiltrate eusocial hives. Their method is sneaky and involves lots of covert affairs that would make any spy proud. First, the female hangs around the nest without trying to get in. She's trying to cover herself in the hive's chemical markup, which is her ticket to getting in. 

Once inside, she usually makes her way towards the brood cells and lays her eggs inside. She may or may not destroy the eggs of the queen. Either way, due to food shortages, her own brood will survive at the expense of the host.

After laying her eggs, she has two options, depending on the species:

  • Run for the hills - attempt to escape the hive undetected or at least with her life;
  • Kill the ruling queen - some species attempt to replace the queen by killing her and covering themselves in her pheromones. This way the cuckoo bee can trick the hive into taking care of several brood generations. However, because cuckoo bees cannot produce workers, the hive is destroyed not long after the death of the rightful ruler. 

Morphological Differences

Biologically, cuckoo bees are a bit different from their host even though they are often (but not always) closely related. There are a few ways you can definitely tell them apart:

Cuckoo bees are a bit bigger - size is definitely an advantage if comes to a showdown between two bees. If the cuckoo bee tries to infiltrate a solitary bee nest and gets caught, she has to fight her way out.

Stronger exoskeleton - for the same reason as above, cuckoo bees have a stronger exoskeleton. This is especially true when their host species is social and they need to get out through multiple stings if they're detected.

Bigger and stronger mandibles - some species of cuckoo bees kill and replace the acting queen of the hive. They need to be well armed for that.

Lack of pollen baskets - since they don't gather their own pollen, cuckoo bees have no pollen baskets;