The degree of oligophagy in Locusta migratoria (L.)

1 Locusta migratoria in the field feeds mainly on grasses, including cultivated species, but there are numerous reports of feeding on other monocotyledons. Feeding on dicotyledons is reported, but in many cases non‐grasses are only accepted in the absence of grasses. Previous laboratory work also indicates that grasses comprise the main food, though other plants are eaten. 2 Field observations on nymphal bands in Australia show that the insects select grasses within the habitat; dicotyledons are generally rejected. 3 The feeding response to 209 species of plants from fifty‐six families was tested. The grasses and some Cyperaceae and Juncaceae were generally fully eaten. Some other monocotyledons, such as palms, were also accepted though only small amounts were eaten; orchids and lilies were rejected. Very few dicotyledons were eaten. The dicotyledons which were eaten after 5h without food were rejected after only 1 h; the grasses were readily accepted after the shorter interval 4 The degree of oligophagy depends on the choice of food available and the time for which the insect has been deprived of food and water. Grass is normally eaten if available; in its absence, insects which have been without food for some hours will feed on a wide range of plants, but the amounts eaten are usually small.