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BULLETIN OF THE UNIVERSITY OF NEBRASKA STATE MUSEUM
SALINE CO. (1): Dewitt; SARPY CO. (5):
Bellevue, Fontenelle Forest; SAUNDERS CO.
(424): Ashland.
Temporal Distribution. Rangewide:
January through December (Ratcliffe 1972).
Nebraska: April (8), May (5), June (54), July
(269), August (2,016), September (12), October
(10), November (3). The large number
for August is a result of a survey in Otoe
County in 1995.
Fig. 50. Nebraska distribution of Necrodes surinamensis.
Remarks. Necrodes surinamensis is distinguished
from other members of the Silphinae
by its large eyes, completely black, orbicular
pronotum, strongly tricostate elytra, and
enlarged femora in the males. The variation
in elytral spots is considerable and was
documented by Ratcliffe (1972).
The egg, larval, and pupal stages were
described in detail by Ratcliffe (1972).
The life history of this species was
studied in detail by Ratcliffe (1972), and a
brief synopsis is provided here. After locating
carrion, adults of Necrodes surinamensis
feed actively on the dipterous larvae that are
present. They mate during the one to seven
days they are at the carcass. The females
oviposit relatively large, cream colored eggs
one at a time randomly on the soil near the
carcass. The eggs (Figs. 51-52) gradually
darken to resemble the soil on which they
rest. Larvae of different instars are found
on the same carcass because eggs are laid
over a span of several days. Larvae normally
hatch from the eggs in 2-4 days and
immediately seek the shelter of the carcass
to begin feeding. Under favorable conditions,
first instar larvae (Fig. 53) molt in 1-2 days.
Second instar larvae molt after 2-5 days. The
third instar stage (Fig. 54) lasts 3-5 days
and, as in all previous stages, may be greatly
extended due to cold or wet weather or poor
food supply. When ready to pupate the larvae
wander a short distance from the carcass
to form earthen pupal cells in the ground.
Pupal cells made in laboratory rearing
chambers were constructed 5 cm below the
surface. The pupal cell is formed by sharp,
convulsive thrashing of the abdomen that
gradually forms an oval, hollow chamber
with firmly packed walls (Fig. 55). After
construction of the pupal cell, a period of quiescence
follows lasting from 5-8 days. This
is the pharate pupal stage, so called because
the new pupa is developing inside the cuticle
of the last instar. Ecdysis eventually occurs