BRN 9-2 (uncompressed) - Flipbook - Page 75
1. Giant Water Scavenger Beetle swims
around an algal mat near the edge of
the stormwater retention pond
(08/24/25), then regularly
swims head-Þrst into the ßoating
algae, which I interpreted as
foraging/feeding behavior.
2. While swimming into the algal mat,
the beetle acquires a passenger, an
Aquatic Long-legged Fly (Hydrophorus sp.) a species common to this
and other regional ponds.
3. Typically, the beetle entered the
algal mat head-Þrst and did not use
the vegetal mat for hiding cover
during our encounter.
4. White oblong/orbs appear in the
water near the beetle's abdomen tip
and hind legs during its displayed
behavior(s).
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5. White orb present in the water near
the beetle's abdomen tip.
6. As the beetle enters the algal mat
again, what looks like newly
released white eggs ßoat in the
water near and behind its abdomen
tip.
7. It appeared to me that this beetle
could be releasing eggs near to and
possibly within this thick, ßoating
algal mat and that perhaps the algal
mat serves a nursery function as
does an egg case until larvae
emerge.
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However, I read several references
that stated that these large beetles
do not deposit eggs directly in open
water; the females all construct a
silken egg case which may be
attached to vegetation or detritus,
allowed to ßoat on the water surface,
or is attached to the beetleÕs
abdomen. As in our leading
photograph, some egg cases may
include a mast that protrudes into the
air above the pond.
Therefore, I concluded that the freeswimming Giant Water Scavenging
Beetle is not ovipositing in open
water or building an egg case, it is
foraging from the algae, eggs
deposited in the algae by several
arthropod species, and small
arthropods including their larval
forms. Free-ßoating eggs next to the
algae were likely placed by female
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