Leafminer on pumpkin
Vegetable leafminer - Liriomyza sativae
American serpentine (or Chrysanthemum) leafminer - Liriomyza trifolii
|Appearance||Eggs: Tiny oval (L. trifolii) or elliptical (L. sativae) white eggs inserted into tissue just below leaf surface.
Larvae: Three tiny, active maggot-like instars that change from pale to greenish to yellow with black mouthparts in all stages (L. sativae), or golden brown turning darker brown (L. trifolii).
Pupae: A tiny reddish/brown non-feeding puparium.
Adults: Very small black flies with yellow markings and abdominal stripes, and transparent wings.
|Life Cycle/Habits||These leafminers are frequently confused, and have similar life cycles. They overwinter in the pupal stage in soil, and adults emerge in spring. There is multiple overlapping generations each year. Female flies puncture leaf undersides and insert eggs individually, producing many small wounds. Female flies are typically most active feeding and laying eggs near mid-day. Larvae are found in mines, tunneling through and feeding in leaves or soft stems (e.g., onion scape). Mature larvae make a slit in the upper leaf surface, emerge and drop to the soil, burrow in shallowly, and form brown pupal cases. Flies emerge in about 9 days.|
Spinach leafminer feeds mostly on spinach, beet, and Swiss chard. The vegetable leafminer has a wide host range, including bean, cantaloupe, celery, cucumber, eggplant, onion, pepper, potato, squash, tomato, watermelon. American Serpentine leafminer is also a significant pest of chrysanthemums and is common in greenhouses.
|Signs/Symptoms||Leaf-mining mars the leaves of leaf crops, and heavy infestations can reduce crop yields. Intensive insertion of eggs may produce slight leaf stippling damage.|
|Monitoring||Look for pale to white leaf mining trails, meandering randomly just below the leaf or stalk surface and readily visible.|