Ants, Beetles, Hoppers and Other Creepy Crawlers
By Neil M. Travis, Montana
It was mid-afternoon on a hot sunny summer day, an occasional
gust of wind would ruffle the surface of the water, and stir
the streamside vegetation. Sitting in the shade of a
cottonwood tree, after I consumed my lunch, I was
contemplating a little afternoon siesta when I began to
notice an occasional rising trout. During the cooler hours
of the morning a sparse hatch of Pale Morning Duns had
provided some action, but that hatch had ceased when the
temperature began to rise. I had planned to rest in the
shade until the sun dropped behind the nearby mountain
hoping that a spinner fall might take place in the cool
of the evening. As I looked upstream, through the glare
of the sun, I could see several sporadically rising trout,
and although I could not see anything on the water the fish
continued to rise. As I continued to watch the action I began
to notice a distinct pattern. Each time the wind would blow,
within a few minutes, the fish would start rising. During the
periods when the wind was still, the number of rising fish
decreased, and suddenly I believed that I had the key to the
mystery.
Selecting a fly from my fly box I slipped into the water
and moved up to casting position below the nearest rising
trout. I waited until a gust of wind swept the streamside
vegetation, and then I dropped my fly a few inches above
where I had last seen the trout rise. My imitation only
floated a short distance before it disappeared in an almost
imperceptible rise. I raised the rod tip and a fat golden
brown trout cart wheeled out of the water, and after several
more jumps and spirited runs slid over the rim of my landing
net. Snug in the corner of his mouth was my imitation, a
black foam beetle. My conclusions had been correct.
After I released this fish I repeated the performance on
the next riser, and this continued for the remainder of
the afternoon. All of the trout were waiting for the wind
to shake the terrestrials from the vegetation and into the
stream. Then it was a very leisurely affair to simply tip
up and sip in a tasty snack. When the sun finally slipped
behind the mountain I decided not to wait for the possible
spinner fall. The afternoon of fishing with beetles had
temporarily satiated my desire to fool any more trout.
Over the years this scenario has been repeated many times
during the hot days of summer. Ant, beetles, bees, hoppers,
and an assortment of other creepy crawlers make up a
substantial portion of the trout's diet during the warmer
months of the year. This is especially true during periods
of hot weather when aquatic hatches are limited or of short
duration. These non-aquatic insects, often referred to as
terrestrials, are far more common than most aquatic insects,
and trout seem to be very aware of this food source.
I believe that these insects become even more important
during periods of drought. During dry periods the only
green vegetation is along the edges of permanent streams
and other bodies of water. Terrestrial insects are attracted
to the vegetation as a source of food and shelter, and may
even become concentrated in this vegetation during periods
when their normal habitat may have become unavailable due
to drought. This is especially true of beetles, bees and
grasshoppers. Even ant numbers may be enhanced along streams
during periods of drought because of the concentration of
insect prey.
Numerous theories have been advanced to explain why trout
feed so readily on terrestrial insects. Some people have
suggested that these insects offer a change of pace and
even a change of taste. Ants have a particularly acrid
taste due to their chemical defense system, and perhaps
the trout find this appealing. However, whenever I have
recovered insects from a trout's stomach they have always
been whole. Trout do not chew small insects, they simply
swallow them whole. It is possible to recover recently
ingested insects that are still alive so I believe that
taste is an unlikely criterion. Rather, I believe that
trout eat terrestrial insects for the same reason that
they seem to relish mayfly spinners, they are easy to
eat. Unlike aquatic insects that are hatching, and
flying away from the water surface terrestrial insects
are generally trapped in the surface film. They are at
the mercy of the currents, and most will never successfully
leave the watery medium. Trout may feed at leisure without
expending a great deal of energy to capture their intended prey.
Watching trout feed on terrestrial insects, especially on
slow flowing streams, is like watching guests at a reception
where finger food is being served. Like guests picking through
the meat and cheese trays trout feed on terrestrials in a
laid-back fashion, tipping up to sample a beetle, then an
ant, and possibly a bee or perhaps a grasshopper. Depending
on their mood, each trout may respond differently to
terrestrials. Some trout will hold in a given spot and only
eat the insects that come directly over them, while others
roam around picking up an insect here and another one over
there. Some trout patrol a certain area swimming upstream
eating whatever strikes their fancy, and then drifting back
downstream and then turning back upstream to repeat the
process. Sometimes this pattern is so repetitive that the
trout seems to be on a preset track going upstream to a
certain point and then turning back down to the starting
point. I prefer the trout that hold in a given location
because they are much more predictable.
Trout feeding on terrestrials are generally less selective
than they might be when feeding on a specific hatch.
Usually terrestrials are a mixed lot with an occasional
ant, some beetles, a stray bee, a leafhopper, or
grasshopper or even a housefly rounding out the smorgasbord.
Occasionally one type of insect may dominate, and then the
trout may become selective. This happens with grasshoppers,
and occasionally with ants.
It was in early September that I encountered one of my
most difficult terrestrial fishing challenges involving
ants. The name and location of the stream shall remain
my secret, but on this particular day a warm late summer
sun was shining, and I was hoping to raise a few trout
on hoppers along a meandering stretch of this stream
that flowed though a heavily grassed meadow. There was
a slight breeze blowing, and I knew the grass was heavily
populated with hoppers. The warm sun made them active,
and I was hoping that some of them would end up in the
water. The stream was low and as transparent as mountain
air after a rain. Along the banks in the deeper pools I
could see an occasional dimple of a rising trout, but
the rise forms were not like trout feeding on hoppers. I
squinted at the surface, and at first I could not see
anything float on or in the film. I tried a number of
various terrestrials but nothing moved the trout. They
continued to feed, sometimes rising within inches of my
fly. Finally in despair I waded right into a spot where
one fish had been steadily rising, and stood staring at
the surface of the water. Then I saw a tiny insect
struggling in the surface film. I quickly dipped it out
with my net, and there was the smallest flying ant that
I had ever seen. Nothing in my fly box, which contained
some size 28 flies, could even come close to matching
this miniscule insect. As I watched the water I saw more
and more of these tiny ants floating down in the flow.
This was truly the unmatchable hatch, and despite my best
efforts to tempt them into rising to some other fly it
was to no avail.
Generally trout feeding on terrestrials can provide great
sport, and during this year of low stream flows and
shortened aquatic hatches anglers should be aware and
prepared to fish these land-based insects. They are easy
to tie, and often very productive. ~ Neil M. Travis, Montana/Arizona
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