I've been wondering for years what this pest actually is. Even though
they infest 25 to 40% of the young apples every year, they tend to not
affect the final crop because the infested apples fall off when they are
small and I do any thinning after that.
It behaves much like coddling moth in that it tunnels in, eats and area
near the center of the small fruit, then exits out the side. I could
almost believe it IS the first generation of coddling moth except for
the following questions:
If it's coddling moth, why does it attack apples that are barely bigger
than a pea, right after petal fall? I find the larvae inside and they
are always small. Far smaller than any coddling moth larva I ever found
in a mature apple. Petal fall was only 2 to 3 weeks ago here and
already, I'm not finding any larvae in the small apples, only the exit
tunnel.
If it's coddling moth, why do I never find them in mature apples? I
can't remember the last time I picked a ripe apple and found coddling
moth damage inside. It's been so long, I'm not sure right now if I EVER
had them here in this yard. (I remember them very well from when I was
younger and living in central Ohio.) My entire spray program for apples
consists of two sprays of Imidan, starting soon after petal fall, then 2
(sometimes 3 depending on the weather) sprays of Sevin when I start
seeing apple maggot flies on my sticky apple traps. With that very
simple spray schedule, my apples have been 100% free of insect damage
for the last 3 years. I would find it hard to believe that Imidan is
completely ineffective on a pest but Sevin is 100% successful at
stopping the next generation.
So, if it's not coddling moth, then what is it? More information: The
entry holes are usually right at the point where 2 small apples touch
each other or where an apple touches a leaf. The frass that comes out of
the exit hole is dark brown but it stains my fingers orange when I break
open the apple to see if there is still a larva inside. The biggest
apple I ever find with an exit hole is about the size of a nickel. Most
drop before reaching that size.