Burying Beetles - From Grave to Cradle University of Florida - Masters Degree class project Cynthia Brast - 2013

1. FROM GRAVE TO
CRADLE?
A Story of the Behavior and Life History of the Burying
Beetle (Silphidae: Nicrophorus)

2. REST IN PEACE?
Burying Beetles are gathered here as
Undertakers of the natural world. To
some, it is a gruesome job…removing
the bodies of small creatures when
they die.
Where do they take them? Do they
eat them? What was that part about a
cradle?
Fig. 1 American burying beetles prepare meal. © Bruce Plante.
Randolph, J. 2011. Can’t Live Without ‘Em: American Burying Beetle.
Defenders of Wildlife Blog. http://www.defendersblog.org/2011/06/cant- live-without-em-american-burying-beetle/
Accessed December 6, 2013.

3. IT BEGINS WITH A
STINKY SMELL!
Burying beetles are sensitive to the
odors from decomposing bodies.
These stinky odors lure them to the
site of the deceased. If a male beetle
arrives first, he is so excited he calls
for a mate by doing a “headstand
waggle” and releasing a pheromone
to attract a female to his “treasure”
that needs to be buried.
The Headstand “Waggle!”
Fig. 2 “Headstand” or “sternzeln” position, from
Behavioral Ecology, 1992. Vol. 3(3), cover illustration.

4. BURIED TREASURE
v When his female partner arrives, the pair face the monumental task of
MOVING this “treasure,” their future “nursery”…to a secret
subterranean location! They begin by finding a suitable substrate,
somewhere the soil is loose and easier to dig through. Crawling over and
under the body that may weigh up to 300 times more than they do, they
pull and push to move the “dead weight” to this softer ground. Together,
they work very fast, concealing belowground in as few as eight hours or
less what will become a bassinet for their soon-to-be family additions!

5. BURIED TREASURE
Once buried, this “grave” for the
newly departed becomes an
underground beetle “condo” for the
hard-working couple. Sometimes if
the carcass is large, there are other
beetle “couples” sharing in this
process and they form a sort of
beetle co-op where they all live
together for awhile.
Fig. 3 Burying a mouse.
Illustration from Scientific American. Inc. (1976)

6. NEXT COMES LOVE…AND
BABY BEETLES!
v Once they complete their new underground home and they don’t
have to worry about a hungry scavenger stealing their “cradle” away
from them, the beetle pair begin preparations for their new family
additions. Turning the buried animal carcass into a nest-like “brood”
ball for their future offspring, they work together again, as co-
parents, to prepare the carcass; removing feathers or fur, and adding
secretions to keep bacteria and fungi from growing in it.

7. POOL PARTY?
v The female beetle creates a passageway in the underground chamber
just above the “brood” ball or nest. She will lay her eggs along the walls
of this tunnel and wait below with her mate for them to hatch. While
they wait, the male and female create a “pool” in the “brood” ball, filling
it with regurgitated fluid digested from the carcass. When the eggs hatch,
the larvae will move through the tunnel and into this liquid-filled cradle to
be tended by their devoted parents!

8. SING ME A LULLABY
Hatching is hard work and the beetle larvae
will need nourishment. Once in the brood
“pool,” their parents play them a
lullaby…not to put them to sleep, but to get
them to to eat dinner. The parents can
make “musical” sounds by
stridulating…sort of like having a built-in-
violin. Then the parent sips fluid from the
pool and transfers it to the mouths of the
larvae as they rise up towards the sound.
Fig. 4 “The Cradle” Feeding of Larvae.
Illustration from Scientific American, Inc. (1976)

9. TINY HELPERS
v Although the beetles do most of the work, sometimes they have
tiny helpers that accompany them and even LIVE with them in their
new home. These tiny helpers are the phoretic mites. No…not
“fairy” mites! Phoresy means they hitch a ride. Yes! You heard right!
There are hitchhikers in this story…

10. THE HITCHHIKERS
v These tiny hitchhikers ride on the burying beetles’ bodies and help them because
sometimes a sneaky fly will lay eggs on the body of the dead animal the beetles find
before they can bury it. If the fly’s eggs hatch first, they will eat and destroy the body or
resource the beetle needs to use for its home, cradle, and food for its young. This is
called competition.
v The mites help the beetle by eating those fly eggs before they hatch so they don’t ruin
all the beetles’ hard work. The beetles help the mites by giving them a ride to a free
dinner. This is called mutualistic symbiosis. They work together and each of them
benefits.

11. TINY HITCHHIKERS…
Tiny Hitchhikers… the phoretic mites!
Figs. 5 and 6 Nicrophorus beetle with phoretic mites.
Photographs by Cynthia Brast. San Juan Island, WA (2010)

12. …AND FROM CRADLE TO GRAVE…
v …and the story ends how? Well, the larvae eat and grow and
crawl out of their “brood” ball cradle. They find a quiet place to
pupate in the nearby soil and eventually emerge as adults in about
twenty to sixty days, but sometimes longer, depending on the species
and environmental conditions. The adult beetles go off in search of a
stinky smell - the scent of their future home. If they’re lucky, they’ll
find a mate…and a grave to call their own!

13. LIFE CYCLE OF A BURYING
BEETLE
Fig. 7 Life cycle of a burying beetle
Illustration by Dakuhippo
http://en.wikipedia.org/wiki/File:Nicrophorus_life_cycle.jpg

14. CONSERVATION
v Burying beetles are important in ecosystems because they help recycle nutrients into
the soil. Plus they keep us from having to smell stinky odors from decaying animals!
Burying a carcass and using it for food and reproduction are the beetles’ way of
participating in the cycle of life.
v Conservation of beetle habitat is important. One species, the American Burying
Beetle, Nicrophorus americana is on the endangered species list. Reintroduction efforts are
underway to make sure populations of these burying beetles don’t become extinct.
Protecting these and other species of burying beetles is important because of their
fascinating bi-parental care of young. They are also useful in reducing competing fly
populations and in reducing risk of disease transmission to livestock and people.