A) Insects damaging shoot tips

Shoot tip flies (genus Lipara)
All 3 species of shoot flies, Lipara rufitarsis, L. pullitarsis, and L. similis are blackish flies whose attack prevents flowering of individual stems. Attack occurs in early summer, a gall is formed and a single larva (maggot) overwinters in the shoot. Although somewhat difficult, all 3 species can be separated by how they change plant growth.

Lipara similis - does not induce a distinct gall. Attacked stems are easily identified by a dried up leaf (instead of a flower) and their stunted growth. A black head capsule and a black last segment identify the maggot. The larva can be found above the growing meristem.

Lipara pullitarsis - Attack by this species causes a swelling of the upper shoot tip. The larva feeds in the uppermost part and does not penetrate the growing meristem.

Lipara rufitarsis - Attack by this species also causes a swelling of the upper shoot where the larva feeds. In contrast to L. pullitarsis, the larva feeds above the growing meristem but for overwintering penetrates it downwards.

The shoot tip mite

Stenotarsonemus phragmitidis - The characteristic damage of this mite is a corkscrew-shaped gall. The mite overwinters in this structure and in May leaves it to infest new shoots. Feeding causes a thickening of the youngest tissue and often prevents complete formation of the flower.

B) Insects in apical internodes

The rice grain gall midge

Giraudiella inclusa - Attack by this midge causes the formation of galls in shape and size similar to rice grains. Although more often found in basal internodes, this species also attacks side shoots formed by Phragmites. A single larva lives per gall where they overwinter. The attack is invisible from the outside.

The “unknown” gall midge

This midge, most likely a member of the genus “Microloasioptera” resembles the fungus growing midge Lasioptera hungarica but without the black mycelium and far fewer larvae can be found per internode. The larvae are paler, there is no obvious mycelium and they are usually found in the upper parts of the shoot and occasionally in side shoots. Larvae of the fungus-growing midge occur in lower and intermediate internodes.

C) Insects attacking intermediate internodes

The fungus growing midge

Lasioptera hungarica - Shoots infested by this midge show no obvious sign of damage, however, they often break in strong winds at the site of attack, suggesting a weakening of the stem tissue. Larvae overwinter in the stem and often 30-300 yellow-orange larvae can be found in a single internode. Characteristic is the black fungal mycelium that the larvae use as food and that is filling the internode. Oviposition by the females also has to infect the internode with fungal spores to assure larval survival. A parasitic wasp commonly attacks the species and birds in certain areas have learned to forage for larvae.

The shoot wasp

Tetramesa phragmitis - Shoots attacked by this wasp show no visible sign of damage. The white larvae live gregariously (2-12) in the shoot, where they also overwinter. The species is often attacked by a parasitic wasp that eats all larvae. The parasite can be identified by a long white cocoon replacing the Tetramesa larvae.

The shoot mining fly

Trypticus sp. - is another shoot mining fly. Larvae of this species are very slender and yellow. There will be only 1 larva per internode but a single larva can attack up to 4 internodes. Larval feeding does not cause any visible damage to the shoot.

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F) Insects found on the outside of the stem or under leaf sheaths of basal internodes

The mealybug

Chaetococcus phragmitidis - has become very common in the Hudson River Valley. The legless red mealybug, which is its common name, lives between the leaves and stems of Phragmites. It is largely invisible unless you peel away the part of the leaf around the stem. Birds have started to forage for these bugs in Phragmites stands.

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                                               Copyright 2002. Bernd Blossey. Cornell University
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