In late August, Jake Price with University of Georgia Extension reported on damage to citrus caused by birds and katydids.
BIRDS
As it is now getting later in the season, fruit are getting larger, and people are noticing more blemishes on fruit.
Birds can cause one type of unusual damage. If you see green fruit that appears scratched or scraped with tiny holes that haven’t quite pierced the skin, that could be bird damage. This damage is often tan or gray in appearance and contrasts with green peels.
Birds will peck at the fruit, often perch on it and scratch it up with their claws. This is what causes the punctures and scrapes. If the punctures go through the rind, the fruit will likely rot and fall off because of secondary diseases. But if the damage is superficial, the fruit will remain on the tree. The fruit will still be edible but will not look good, so it cannot be sold commercially.
Usually there is not enough bird-damaged fruit to be concerned about. But if you see this damage, it is likely your citrus trees are providing nice habitat for birds to hide and nest.
KATYDIDS
There is another type of damage to citrus fruit caused by an insect that looks like a grasshopper, called a katydid. These insects are green and well camouflaged. They develop flat wings as adults, which make them look like a leaf.
If you find a fruit that appears to have scar tissue that is very different looking than the peel, that is likely caused by the feeding of a katydid. Immature katydids (nymphs) will feed on the fruit when it is small, often smaller than a dime. The feeding pattern is often roundish in shape but can be irregular.
If the fruit doesn’t fall off, it will form a blemish that looks like a light gray or tan scar. This blemish is often very distinct from the normal green citrus peel.
The damage from these insects is usually not widespread enough to be a problem in commercial groves, but it will make the fruit unsellable.
In early spring, growers can often find flat, oval egg casings of katydids embedded in the edge of a leaf. The nymphs will emerge in April and May, leaving a tiny hole in the egg casing.
Source: University of Georgia College of Agricultural and Environmental Sciences