Late spring spinach (note the outline of a worm in bottom corner)
Flat of Egypt beet greens
The small gray flies lay their eggs in neat little clusters on the underside of the leaves.
As the maggots emerge they get in between the leaf tissue mining their way throughout the leaves as they feed.
The first of the many cycles they go through each year seem to be the most damaging for our crops and as the season progresses the damage inflicted becomes less noticeable. The only solution I have come up with to combat these little nasties is to pull off the tunnelled leaves and feed them to our ravenous chickens.
On a smaller scale one could attempt to destroy the egg clusters before they hatch but we grow too much chard for that to be a practical solution to the problem. I have noticed a huge number of parasitic wasps going after the maggots in the leaves but the pests still seem to outweigh the predators.
One thing I am going to do is allow the birds into the garden for a brief period this fall and the following spring to help combat any overwintering insects. If anyone has found an organic method of relieving themselves of these exasperation's please do tell.
"Too close a look can oft temper ones enthusiasm for a natural salad" - Mike :)