Ground beetles (Carabidae) are one of the largest and most successful families of beetles in the world. These beetles can range in size from 1/8 inch to 1 inch long and typically have a dark-colored, streamlined body with ridged wings.
There are more than 40,000 species of ground beetles in the world, most of which are found in the tropics. On the other hand, Britain has around 350 species. The largest species in Britain is Carabus intricatus, which is very rare and can only be found in a couple of places on Dartmoor.
Not only are beetles fascinating and easy to find, but they are relatively easy to keep in captivity and will readily reproduce—so that you can study all of their life cycles.
Whether you want to observe a ground beetle in its natural habitat or keep one as a pet, here is a guide on how to find and take care of a ground beetle.
We’ve included everything you need to know about these creatures, including where to look for ground beetles, how to capture and transfer them safely, and what types of food and habitat they prefer.
How to Effectively Find Ground Beetles
You may think that finding ground beetles is a simple task, but there are actually a few tips and tricks to keep in mind.
First, it’s important to understand their natural habitat and behavior. Ground beetles are nocturnal creatures that prefer dark and moist environments, such as under logs, stones, or leaf litter. They also have strong hind legs, allowing them to quickly move away if they sense danger.
With this in mind, the best time to search for ground beetles is at night with a flashlight or headlamp. Look under logs, rocks, and foliage to spot any potential beetle hiding spots. You may also want to try using an insect net to sweep through grassy areas and look for moving insects among plants.
Another method for finding ground beetles is to attract them by setting out bait, such as overripe fruit. Place the bait in a dark and moist area, check back periodically, and you may find some ground beetles feasting on the food source.
Housing of Ground Beetles
Plastic storage boxes or washing-up bowls make suitable cages to keep your pet beetle in. A layer of peat (or coir compost) or sand needs to be put in the bottom.
This must be kept moist (but not wet) at all times. A shelter must be provided; this can be a large stone or up-turned flower pot saucer.
Beetles love to hide under logs, so consider placing a small log or bark in their enclosure for them to hide under.
Regularly cleaning the cage, at least once a week, is important to prevent the build-up of waste and mold.
Watering daily with a spray bottle and occasionally misting the enclosure will provide enough moisture for your beetle
Feeding Ground Beetles
As with any pet, beetles also need a proper diet to stay healthy
Most Ground Beetles are omnivorous and can be fed on a variety of foods such as fly larvae, small seeds, ant pupae (sold as ant eggs for fish food), aphids, or any other small insects.
Some species however, are specialist feeders, i.e. Harpalus rufipes (the Strawberry Seed Beetle) feed on seeds; Loricera pilicornis (the Springtail Beetle) feed on Collembola; and Abax parallelopipedus (ater) and Cychrus caraboides feed on slugs and snails.
The larvae are generally carnivorous—and always so if the adults are. This means that if their food source is limited, they may cannibalize each other.
It is important to provide enough food and regularly clean out any uneaten food or waste to prevent this from happening.
This isn’t too much of a problem if they are kept well-fed and not overcrowded, but it may be a good idea to take out any larvae found and keep these in a separate container to prevent cannibalism.
Abax parallelopipedus is a species that is not cannibalistic and therefore makes a very good pet beetle or study animal. It can often be found under rotten logs in woodlands.
Breeding Pet Beetles
Breeding beetles is not a skill that comes easily, as it requires patience and attention to detail. However, with proper care and monitoring of your beetles’ environment, you may be able to successfully breed them in captivity.
Different Ground Beetle species are unofficially classified as either Spring or Autumn breeders. Spring breeders such as Pterostichus cupreus over winter as adults, while Autumn breeders such as Nebria brevicollis over winter as larvae.
In general, the number of eggs produced depends on nutrition, environmental factors such as moisture, temperature, and the age of the beetle.
Research indicates that Carabids in the wild seldom reach their reproductive capacity. As in most predators, egg production is related to the food supply.
It has been found that the number of eggs produced is inversely related to body mass; hence, large species lay fewer eggs and that autumn breeders tend to lay more eggs than spring breeders.
Also, members of a given species tend to lay more eggs in disturbed conditions than in stable ones. In the first year, females will lay 5-10 eggs (in those species with egg-guarding behavior), but up to several hundred in those that don’t.
Eggs are laid all in one batch, as several batches per season, and in some species, over several seasons. While in the second year, in most species, far fewer or no eggs are produced.
Some species lay their eggs individually on the surface of the soil, while others dig holes and lay their eggs in them before covering it over with soil.
A few species dig nests with chambers and provide brood care in the form of guarding the eggs and licking them to remove fungal spores (e.g. Harpalus sp.). The eggs normally take at least five days to hatch depending on the species and environmental conditions.
Ecology of Beetles
Now that you know about the care and feeding of Ground Beetles, it is important to also know about their ecology since this will help inform you how to properly care for them in captivity.
There are usually 3 larval instars before pupation, but species of Harpalus and Amara have only 2 larval instars; while other species, particularly those which are an ant or termite symbionts, have four larval instars. Many species diapause (overwinter hibernation or summer aestivation).
In general, development takes about a year from egg to egg laying, though it can take up to four years in harsh conditions, i.e. Carabus problematicus is univoltine until 800 meters in height, then becomes semi-voltine.
This means that at lower altitudes, they go through one full developmental cycle per year, while at higher altitudes they may take longer.
Other species such as Carabus auronitens are more flexible and adapt to the prevailing conditions. A pupal chamber is constructed in the soil. They normally take at least 5 or more days to emerge from the pupa.
We have gone over the basics of breeding and caring for Ground Beetles in captivity. However, it is important to note that each species has its own specific needs, so always do your research before introducing a new beetle into your care.
In addition, remember that these animals play an important role in their ecosystems as predators and decomposers, so make sure to release any excess breeding stock back into suitable habitats to maintain the balance of nature.
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