Phytomyza glabricola

The inkberry leafminer is one of many related leafminers. It only mines and develops on the leaves of inkberry. Blotch mines are created by the larval feeding of this insect. Two generations are said to occur per year, however several may be possible and the life cycle in Massachusetts is not fully understood. (Adult emergence has been observed in early May in Massachusetts, Childs, Personal Communication.) On Ilex glabra, development time of this insect takes approximately 2-4 weeks. Adult flies emerge on both aforementioned hosts synchronously, around mid-January and mid-February in southern portions of its range (Herbert et al. 2016). However, the life cycle of this insect in New England is not currently well understood. In Ohio, two 1st instar larval peaks were observed in September and December and also again in June of the subsequent year of observation. Peak timing for 2nd and 3rd instar larvae of the Ohio populations observed was less obvious. In this study, peaks of pupation were observed in July and again in September with adult activity peaks in August and October. In a subsequent year of observations, adult flights were again observed in April, May, June, July, and September in Ohio. The data from this study varied depending upon whether the site was in the shade or sun. Four generations per year were estimated by their observations (Al-Siyabi and Shetlar, 1999). This study also estimated that in Ohio, inkberry leafminer pupae are the overwintering life stage. Al-Siyabi and Shetlar also observed that unlike the holly and native holly leafminers, inkberry leafminer adult females did not produce pinholes in host plant leaves and did not seem to feed on inkberry sap in their field observations (1999). Three or four generations are thought to occur per year in Ohio. Additional, related leafminers (holly leafminer, native holly leafminer) are found on similar hosts.