Alaus spp.

This caresheet should cover all US Alaus species, and may also be applicable to species found outside the US. 

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Housing:

Adults can be kept in any kind of tank or plastic container, just make sure they aren't very crowded, for the US species a half a gallon container would be the smallest I'd house a pair of adults in, whilst a starter group of half a dozen adults or so should have at least a gallon or two of space. They should be provided with a substrate of fine coconut fiber, sphagnum peat, or flake soil, at least a centimeter or two deep. They will appreciate hardwood bark hides and such to cling to and rest under. The enclosure should be moderately to highly ventilated, and the substrate kept moist at all times.

Small larvae can be kept in 2 oz deli cups filled with a substrate of somewhat compressed, moist substrate, until they reach almost an inch in length. After that they will need something bigger, 16 oz deli cups or something of a similar size will work well, again filled nearly to the top with substrate. Once the larvae reach 1.5 to 2 inches in length they should be moved to a 32 oz deli or larger. Then they should be set for the rest of their larval stage and will pupate comfortably in such a container.

Unlike a lot of other click beetles, at no life stage do Alaus seem to require rotten wood in their diet or to induce oviposition, so the substrate can consist of any fine soft substrate, such as coconut fiber, sphagnum peat, or if you have some to spare, flake soil. However, the pupae of A.melanops refuse to pupate unless they have wood to bore into to construct a pupal cell (the wood doesn't even have to be that rotten, just soft enough for them to bore into). It seems like most other Alaus species will create their pupal cells in moist, compressed substrate though, but sometimes only after a while of wandering around the substrate looking for a chunk of wood to bore into.

Perhaps most importantly, ALL live stages require consistent and high humidity, dryness is the only thing that kills larvae of these beetles easily, and yet it seems to be a fairly common problem that people have, as they tend to forget to feed and water their larvae... While larvae (especially larger ones) can go quite a while in between feedings, if their substrate is allowed to dry out completely they will die.

Diet:

The peaceful adults feed on fresh fruits like apple and banana, beetle jellies work fine for them as well.

The larvae on the other hand, are completely carnivorous from the moment they hatch, and only consume living or pre-killed invertebrate prey.

For live prey, beetle larvae such as mealworms are recommended, they can not catch fast moving, non burrowing prey and specialize on eating other beetle larvae in the wild.

For pre-killed prey you can use beetle larvae, roaches, crickets, etc., as long as it's soft bodied and meaty they'll love it. Large larvae have even been fed dead pinky mice in captivity, though insects are probably healthier for them.

It should go without saying that because of their nature, the larvae are quite cannibalistic from the moment they hatch, and therefore the desired amount should be isolated from the breeding container as soon as you notice hatchlings.

Larvae should be fed every couple days for optimal growth, but can go quite a while in between feedings. Watch out for grain mites and remove any uneaten food a couple days after feeding, mites and dryness are really the only things that can easily overwhelm and kill the larvae of this species, they are very hardy otherwise.
Also, be sure to use relatively small prey items for smaller larvae, especially when using pre-killed, because if the prey item is big enough small larvae may bore into it when feeding, and you may accidentally throw them out with the prey when it comes time to replace it. 

Temperature:

A temperature range from 72-75F° seems work best for all immature life stages of most species, but the adults of most species seem to like it a bit warmer for optimal breeding/oviposition, more like 75-80F°. All life stages can likely take warmer temps, up to 90F° or so, and while this may even make the larvae grow faster, that excessive warmth could potentially lead to them maturing into rather small adults.

Breeding/Life cycle:

Adults live for 4-6 months, depending on the species and temps. Females lay at least 50-80 eggs each, which are quite large for Elaterid eggs and perfectly spherical. Larvae typically start hatching out after less than month, and are TINY, around 3 mm long.

As I mentioned before, they are fully predatory and cannibalistic from the first instar, so the desired amount should be separate from the breeding container asap. Thankfully due to how prolific female Alaus spp. are, the cannibalism shouldn't be too much of a problem, and it's still pretty easy to keep multiple generations going and have plenty of excess larvae.

Most larvae usually take about a year or two to complete development under optimal conditions, all depending on the species, feeding frequency and ambient temps.

After they are fully grown, the larvae of most species will construct a pupation chamber towards the bottom of their enclosure in the same manner as most Tenebrionid larvae, they just push substrate up and away from themselves until a little chamber has been cleared out (one exception being A.melanops, which make chew out their chambers in solid wood). Their cells lack the thick saliva/frass reinforced walls that scarab beetles make, so be sure not to dig them up or anything. Leave them alone during this stage, just make sure they don't dry out. The larvae sit in the pupal cell for a few weeks, then molt into a pupa, which will then take about 1-2 months to develop into an adult, depending on species and temps.

Once the adult ecloses, it will typically take another week or two for it to dig it's way up to the surface, let it do it's thing, no need to try to dig it up by yourself in an attempt to help it, (though it's not particularly harmful to do so, as long as the beetle isn't very freshly teneral). Once it rises to the surface, you may remove it from the deli cup and put it in a breeding enclosure with other adults. Then the cycle begins anew. 😊