Rhododendron Tip Midge
Adult -The rhododendron tip midge is a light-brown, 1.25-mm-long fly. The hairy male has antennae 1.5 times the length of its body. The female, on the other hand, has a short ovipositor and antennae about as long as its body.
Egg -The egg has not been described.
Larva -The flattened maggot is whitish and about 1.27 mm long.
Pupa- The pupa has not been described.
Host Plants -Rhododendron is the only known host of this pest.
Damage -Rhododendron tip midge maggots feed exclusively on tender new growth. Young infested leaves, usually less than 5 cm long, develop inwardly rolled margins with swollen, greenish-yellow tissue. The margins may fold over the midrib. Lightly infested leaves have palegreen bulges over most of the surface and become stunted and distorted. On severely infested plants, new growth may be so distorted after emergence that additional foliage fails to develop.
Life History -These pests overwinter as pupae in the soil. The adult flies emerge and lay eggs in the spring as new plant growth develops. The newly hatched larvae protect themselves by feeding from within the curled leaf margins. When mature, the maggots drop to the soil to pupate. Damage first appears in late May or early June and often reappears in August on the second flush of growth. Therefore, it seems that at least two generations occur each year.
Heavy infestations of this pest are unusual and sporadic. An effective cultural control method for both homeowners and nurserymen is the removal and destruction of newly infested foliage. This practice may eliminate an infestation within a single year or two. No chemicals are currently registered for control of this pest.