Biology and rearing of the cogongrass gall midge, Orseolia javanica Kieffer & Docters van Leeuwen-Reijnvaan (Diptera: Cecidomyiidae)

Imperata cylindrica (L.) Beauv. (Poaceae) is one of the most harmful weeds in the world because of its ability to spread and form high density, monospecific stands that exclude other vegetation. The cogongrass gall midge, Orseolia javanica Kieffer & Docters van Leeuwen-Reijnvaan (Diptera: Cecidomyiidae), is a stem galling insect that is only known to develop in cogongrass and has only been found on the island of Java in Indonesia. The midge attacks very young shoots, which stimulates abnormal growth, resulting in the formation of a purplish, elongate stem gall tappered to a point at the apical end. The aim of the current research was to describe the biology of the midge and develop a rearing method. Orseolia javanica completed its life cycle in 12-38 days with average egg, larval, and pupal periodes of 4.0 +/- 0.0, 13.5 +/- 3.8, and 8.6 +/- 6.6 days (mean +/- SD), respectively. Mated female, unmated female, and male longevities were 1.7 +/- 0.47, 1.2 +/- 0.41, and 1.0 +/- 0.00 days (mean +/- SD). Galls began to appear 29 days after larval infestation, and stem death coincided with emergence of the adult midge. The midge may have potential for biological control of cogongrass if future studies confirm a restricted host range.