GRAIN APHIDS IN NEW BRUNSWICK: II. COMPARATIVE DEVELOPMENT IN THE GREENHOUSE OF THREE APHID SPECIES ON FOUR KINDS OF GRASSES

The development of three grain-infesting aphids, Rhopalosiphum padi (L.), Macrosiphum avenae (Fab.), and Rhopalosiphum maidis (Fitch), was studied on four members of the Gramineae: Avena, Triticum, Hordeum, and Poa, in the greenhouse. Wingless R. padi developed most rapidly irrespective of host. In general, winged forms took longer to mature than wingless forms of all species except R. maidis on Avena. Hordeum was the preferred host of all species and on this host R. padi produced per adult 59 nymphs, R. maidis 49, and M. avenae 37. The mean length of life of all species on all hosts was 28.8 days but wide variations occurred on different hosts. Neither R. padi nor R. maidis accepted Poa, nor did R. maidis survive on Triticum under our conditions.