Stag beetles have a very secluded long life cycle, spent mostly underground, and this page is an attempt to illustrate it step-by-step. Understandably there are still a few gaps to cover, so contributions are always very welcome.
Breeding season: end of May until the beginning of August out in the open air.
Eggs: 12 to 24 laid in next to rotting wood. The female may take a long time carefully preparing her nursery, digging around, chewing pieces of wood, and compacting them near the dead wood. As each egg is laid she uses her retractable ovipositor to form a hollow around it, exactly like some dung and burying beetles do. [1]
Larval development: nobody knows for sure. However, recently it has been observed that it took less than 4 years feeding on decaying oak posts in the wild. [2]
Moreover, from some captivity studies, it is now known that the tiny larvae may undergo at least five instars before they are ready to pupate. [3]
Pupa: between three and six weeks during the summer inside a cocoon, in the soil, made of compacted soil [3]. In the wild prepupation gets well under way before the end of July.
Adult stag beetle: may stay inside the cocoon or not. In any case it will always remain under the ground for several months until it emerges in the summer to fly outside.
 Stag beetles clinging to ivy in the mating position. Photo by John Allen. |
 Stag beetles mating during the evening under a car. Photo by Maria Fremlin, 7 June 2003. |
 Male stag beetle attempting to mate with a dead female. For another photo click here. Photo by Maria Fremlin, 6 July 2007. |
 Eggs from a female that had been killed by a predator. They are surrounded by fat. Photo by Maria Fremlin. |
 Magnified view of fertilized eggs at the very early stages. Note how the eggs have changed shape. Photo by Dr Eva Sprecher. |
 An even more magnified view of an egg showing the larva developing inside it. The egg has grown a bit, it is now 3 by 3.4 mm. Photo by Dr Eva Sprecher. |
 First instar: age - two days weight - 0.02 g HCW - 2.4 mm length - 5 mm Photo by Dr Eva Sprecher. |
 Second instar: age - twenty two days weight - unknown HCW - ~5 mm length - ~4.5 cm Photo by Paul Hendriks. |
 Third instar: age - ~4 months weight - 3.3 g HCW - 10 mm length - unknown Photo by M. Fremlin. |
 Third instar: age - unknown weight - 21.5 g HCW - 11.95 mm length - 8 cm Photo by Bert van Geel. |
 Male stag beetle pupa. Photo by Michele Zilioli, September 2005, Italy. The larva was collected in the wild feeding on a rotting oak stump, Quercus petra, and then reared in captivity. |
 Female stag beetle pupa. Photo by Paul Hendriks, November 2007, The Netherlands. Reared in captivity from eggs laid in July 2006. |
 Male stag beetle found inside its cocoon, late May. It was at 40 cm depth, near the rotten roots of an ash (Fraxinus spp.) tree where stag beetle larvae were also found feeding. Click on the picture for another view. Photo courtesy of Heinz Rothacher. |
 Female stag beetle found inside its cocoon, early April, 2006. It was in the roots of an old oak (Quercus robur) stump, about 3 meters high. There was also 1 larva, 7 females, of which one was dead, and 14 males, of which 4 were dead. Photo by John T. Smit. |
 Stag beetles will make their way up to the surface and emerge through holes like this one. They do it with the help of their mandibles and their front legs which are also very strong. Photo by Maria Fremlin, late May. |
 Male stag beetle with fully spread wings ready to take off from a lawn. Photo by Neil Postlethwaite, early June during a flying night. He told me that "during the same night, as late as 11:30 pm, something crashed onto the road next to the hedge out of the air. When I wandered over to have a look, instead of finding a stag, I found just the head still wriggling, no body and a set of wing cases". Bats? |
[1] Orin McMonigle, 2004 - The Complete Guide to Rearing the Elephant Stag Beetle and Other Stags. Rearing techniques for stags from around the world with emphasis on Lucanus elaphus. 2 color plates. Elytra and Antenna.
[2] John T. Smit & Paul Hendriks, 2005 - Broedstoven voor vliegende herten - Breeding sites for stag beetles.
[3] Deborah Harvey and Alan Gange - The Private Life of the Stag Beetle ( Lucanus cervus). The Bulletin of the Amateur Entomologists' Society, 2003, Volume 62, Number 451, 240 - 244.
Links:
Life cycle photos of Lucanus capreolus.
Insect life cycles, an English site by David Kendall, it has some interesting life cycle diagrams.
Last modified: Mon Sep 28 14:48:29 GMT 2009
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