The most dangerous pests that develop and feed in mid-field woodlots are aphids. In some seasons they lay eggs and feed within woodlots on woody plants, such as spindle trees (Euonymus spp.), guelder rose (Viburnum opulus), mock orange (Philadelphus coronarius) and buckthorn (Rhamnus cathartica), which are rare in woodlots, or hawthorns (Crataegus spp.) and bird cherry (Prunus padus), which are more common there.