Gouty Pitch Midge

Cecidomyia piniinopis O.S.

From: Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54

Hosts. – Ponderosa pine; occasionally lodgepole pine.

Distribution. – Throughout host range.

Damage. – Attacks occur near branch tips in early summer. New shoots fade, droop, turn yellow, and die. Repeated attacks which do not kill the shoots may twist and stunt branches. Beneath the bark, small resinous pockets are formed by developing larvae. Trees 4-16 feet in height are most heavily infested. Small trees may be killed.

Identification. – Needles on infested shoots die in tufts which soon droop and turn yellow. Later they become red-brown (fig. 86). These flags are scattered over part or all of the crown and appear by summer. Extensive twig killing, stunted or distorted growth, and sparse, off-colored foliage are symptoms of persistent heavy infestations. Infested shoots will have slight swellings on their surface which enclose bright orange to red maggots about one-eighth of an inch long (fig. 87) from July to the following June. The resin infiltrates the wood around pits and sometimes exudes over the twig.

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Figure 86. – Damage to infested shoots caused by Gouty Pitch Midge.	Figure 87. – Gouty Pitch Midge maggots within branch swelling.

Larvae overwinter in pits under bark. Adults emerge in early spring after larvae migrate to surface of branch to pupate.

Similar damages. – Damage is similar to Diplodia blight. Pitchy "gouts' on twigs and larvae, when present, distinguish this pest.

Link to Images in Forestry Images

References.

Anonymous. 1982. For. Insect & disease identification and management. USDA For. Serv., Northern Region; Idaho Dept. of Lands, Insect and Disease Control; Montana Dept. of State Lands, Division of Forestry. 192 p.

Eton, C.B., and J.S. Yuill. 1971. Gouty pitch midge. USDA For. Serv., For. Pest Leaflet 46, 8 p., illus.

Furniss, R.L., and V.M. Carolin. 1977. Western For. Insects. USDA Forest Serv., Misc. pub. 1339, 654 p., illus.

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