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Dynastes hercules (page 6)

Further photos of the emergence sequence of a male D. hercules, and a comparison between the "major" and "minor" physical forms of the species.  Photos courtesy of J. Lai.

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It has now been about two weeks since the male emerged from its pupal skin, and the elytra are beginning to take on a light brown hue.  Still, this color is only truly apparent when the insect under low humidity conditions.  As with the other lightly colored Dynastes species, changes in humidity alter its coloration.  Moist conditions make the beetle turn dark, while drier conditions cause it to become much lighter.
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Dynastes hercules (male) recently emerged - Image  J. Lai

 
Dynastes hercules (male) freshly emerged - Image  J. Lai
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Here the same male is shown 50 days after having emerged from the pupal skin.  Final coloration has now been reached.  The time period needed for this individual to become its final color was approximately 30 days.
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Another photo of the same male, this time shown with an apple for size comparison.  Dynastes hercules is surely one of the world's most spectacular rhinoceros beetles in respect to size, ornamentation and color, and certainly one of the most famous of all tropical insects.
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Dynastes hercules (male) recently emerged - Image  J. Lai

 
Dynastes hercules (males) - Image  J. Lai
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There is a great variation of adult size in D. hercules, especially in the males.  The small male shown at left in this photo is what is referred to as a "minor" male, whereas the one to its right is called a "major".  The size difference is largely the result of nutritional factors during the larval stage, although it is thought that temperature may also possibly play a role.
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A dorsal view of the same two males.  Male D. hercules can range in size from between 45 mm and 170 mm.  The small male shown in the photo is 77 mm, so he is at the higher end of the small size range.  A variety of sizes occur in both the wild and under captive reared conditions.  The same is true of other large dynastine scarabs such as Chalcosoma caucasus.  The reasons for these variations is not yet well understood, although it appears to be more directly related to the level of nutrients that the beetle obtained as a larva, rather than genetics.
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Dynastes hercules (males) - Image  J. Lai

 
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