Sunday, 21 December 2008

#58 Christmas beetles get busy

Christmas Beetles are busy passing on their genes at this time of the year, and I am particularly pleased with the series of images I captured of one species in action.

Over two days in mid December, I found Black Nail Beetles (Repsimus manicatus) in numbers on a couple of my Callistemon shrubs. With a ladder, and a good dose of patience and a healthy sense of discovery and humour, I searched for mating pairs, and was rewarded with good views of the entire act.

Black Nail Beetles (Repsimus manicatus) are so called
because the elytra (wing covers) resemble long black
polished fingernails


Adult beetles emerge during the early to mid summer period from the soil, hence the common name of "Christmas Beetles". From Family Scarabaeidae, there are approximately 34 species of Christmas Beetles distributed throughout Australia, most commonly in the high-rainfall coastal areas of eastern states.

Life Cycle of the Christmas Beetle

The life cycle extends over one or two years, depending on species. Eggs are laid into soil or compost in the spring and early summer. Females are capable of laying between 20 and 40 eggs each. Newly hatched larvae feed on organic matter in the soil, and older larvae feed on organic matter and/or roots. Ref: Dept Primary Industries, Queensland.

The larvae have a distinctive 'C' shape and are often called curl grubs. In late winter/early spring fully-grown larvae move close to the surface and hollow out a chamber in which they pupate. Pupation lasts several weeks.

After pupation the new adults must wait in the soil for suitable conditions, usually when the soil is softened by rain, allowing them to dig their way to the surface. In very dry conditions the beetles cannot burrow to the surface, and die in the soil. In flooded conditions they will drown. Ref: Dept Primary Industries, Qld.

The underside of a Black Nail Christmas Beetle as it eats


After emerging, beetles fly a short distance to food plants to feed and mate. The females then return to the soil and lay eggs, although some lay eggs before feeding. Feeding and egg-laying may continue for several days. Adults may live for some weeks. Ref: Dept Primary Industries, Qld.

Adults are voracious feeders and large swarms can rapidly defoliate trees. Although the damage to my Bottlebrush shrubs is evident, it is not extreme, and a light prune will be all that is needed to tidy them up.

Black Nail Beetles ( Repsimus manicatus) copulating.
- notice the distinctive difference in size and
shape of the hind legs of male and female.


The Black Nail Beetle has immensely developed hind legs, with the male having thicker legs than the female. When I disturbed the beetles, they raised back legs in a horizontal posture, presumably to assume a more threatening size as a defense strategy.

It was interesting to note that the Black Nail Christmas Beetles were not attracted to the porch light of a night.

The large hooked back claws are not used in mating,
but for moving about the foliage


This image shows a thick white fluid oozing from
the female's reproductive canal


. . . . . and this image illustrates the shape of the male's
reproductive organ just withdrawn from the female


It might sound like a rather odd pastime, spying on the mating practices of beetles, but what fascinating up-close observations! And all in my garden! This is the first time I have noticed this species of beetle in my yard, so it was a beaut find.

***** ***** *****

Christmas is different things to different people. I hope everyone stays safe over the festive season, and has reason to smile. I'd like to send a special "cheerio" to those who might be lonely, alone, unwell, low in spirit, or down on luck.

Seasons greetings from Gaye from the Hunter

12 comments:

William Archer said...

Hi Gaye
Very informative as usual with great photos. Just gos to show the breadth of wildlife in the garden if you care to look.
Merry Christmas Gaye
William.

elfram said...

What handsome beetles, and what a handsome blogger!

MissAnthropy said...

Awwww, "love in a hot climate"...great photos!

A happy Christmas to you and your loved ones and thank you for a year of sharing your excellent observations.

Aussie Christmas:
The north wind is tossing the leaves,
The red dust is over the town;
The sparrows are under the eaves,
And the grass in the paddock is brown ,
As we lift up our voices and sing
To the Christ child, the heavenly King.

Podzol said...

Fantastic close up photos!

Those hooks are huge!

Best wishes for a happy Hunter Valley Christmas.

Gaye from the Hunter said...

Hello all.

William, thank you. It also goes to show the value of enthusiasm when one (like me) does not have knowledge gained from education or field experience. It is my hope that through the sharing of my observations, I can encourage others to take a closer look around them and to appreciate and enjoy the environment right at their back door.

Elfram, why thank you good sir.

MissAnthropy, thank you for the poem. It is one I have not heard, and produced a smile.

Podzol, thank you. They most certainly are huge hooks, and when I first saw them, I was also amazed. I presumed that they would be used in a mating grapple, but I was amazed at the gentlemanly manner in which the males handled the females. I was also amazed that the mating process was not a static affair, but an active act lasting a few minutes.

Thank you all for taking the time to leave a message, and Merry Christmas to you and those you hold dear.

Denis Wilson said...

Hi Gaye

Many thanks for the interesting post. I have never seen hat species.

Have a very Happy Christmas, and your family too.

Cheers

Denis

Boobook said...

Excellent photos Gaye, and excellent patience.

Tyto Tony said...

Super post! Good on you, Gaye. Seems up this way the beetles don't have much sense of Xmas timing. Maybe a tree thing?

Gouldiae said...

G'day Gaye,
Great shots and plenty of informative text. Another very readable entry. Keep up the good work.
Compliments of the season to you and yours.
Regards,
Gouldiae

Duncan said...

You voyeur you!! ;-)

Gaye from the Hunter said...

hello all.

Thank you for leaving comments, and Seasons Greetings to all.

Cheers
Gaye

Robyn Carlisle said...

Gaye Love your blog !
I am glad I am not the only woman photographing beetles mating. I too have a blog and was so pleased to catch this moment in creation
Regards Robyn