This very common pest of beet, spinach, and Swiss chard is a type of fly. The maggots hatch out and feed between the upper and lower leaf surfaces producing serpentine and blotch mines. It overwinters in the pupal stage with adults emerging and mating outside in April/May.
Locating and squishing these egg masses will help reduce their population. Row covers placed over seed beds and new transplants can help exclude the mated females and prevent egg laying.
|Two egg masses on underside of beet leaf|
|Eggs are white and eliptical in shape|