The garden symphylan is an occasional but very destructive pest of field crops.
Most problems occur in the eastern half of Pennsylvania.
Symphylans overwinter in the soil as adults. In the spring, they move up into the top 6 inches of soil when the soil temperature rises about 45 F. Eggs are deposited in late April, in May, and in June. The eggs hatch 2 to 3 weeks later into tiny, white nymphs that resemble the adults except that they have only six pairs of legs. Control of garden symphylans involves preventive treatment before or at time of planting. No rescue treatment is effective while the crop is growing.