[3] The midge induces stunted and distorted rosettes[4] in the host by inhibiting the elongation of the shoot; the rosette is formed from many (8 to 40 or more) slightly thickened and deformed leaves with reduced petioles.

Many of the leaves have small green or red ligulate excrescences or projections.

[3] Adults emerge from pupae in the ground beneath the shrub and the terminal bud infestations start in March or April; the fully grown larvae fall to the ground in September or October to undergo pupation after feeding and sheltering within the leaf rosette for some time.

[3] The hawthorn button-top gall midge shows a scattered distribution throughout England, however it is an under recorded species.

[6] Aprostocetus lysippe is a hymenopteran insect of the family Eulophidae and a parasitoid of D. crataegi.