A novel non-destructive method was devised for studying the development of insects hidden within individual wheat grains using a standard nuclear magnetic resonance (NMR) spectrometer. The development of Sitophilus granarius (L.) at 25°C and 70% RH was studied from egg-laying to emergence by NMR, X-radiography and weighing. The results of the three methods correlated quite well. Neither the NMR nor the X-radiation appeared to harm the insects. The NMR method did not usually detect the insects until they were in the third larval instars, but after that the areas of the two NMR peaks observed with each infested grain followed a pattern which was readily interpreted in terms of the insect development. The major NMR peak was found to be due almost wholly to water and the minor peak to lipid, and the size of the major peak obtained with adults was close to that expected on the basis of their water content. The movement of some of the insects within the grains was observed for short periods and appeared to be characteristic of each developmental stage. Preliminary work with a less sophisticated NMR machine showed that it is possible in a single scan to detect ten grains infested with S. granarius larvae in a batch of 500 grains, but further work is required to see whether single eggs can be detected. The results obtained in this study were sufficiently encouraging for a wide variety of other areas to be suggested in which use of NMR might help to solve some entomological problems.

Alatae of Aphis fabae Scop. which reproduced before their first flight (flyers) were compared in the laboratory with those which did not (migrants) in order to test whether this difference in behaviour could be taken as an expression of migratory urge. No difference in live weight or dry weight could be found between the two groups. Flyers, however had a higher wingloading than migrants after the final moult but not after pre-flight reproduction. Flyers also had a lower fat/dry weight ratio than migrants and appeared to have more embryos, including a greater number in an advanced state of development. The significance of these observations is discussed in relation to two hypotheses which could account for the different behaviour of migrants and flyers. The results support the hypothesis that migrants have an innately greater urge to take off than flyers, mediated by their crowding experience during development, and that this is likely to result in migratory as opposed to trivial flight.

Parapyrus manihoti gen. et sp. n., an encyrtid parasite of Phenacoccus manihoti Matile-Ferrero in South America, is described from the adults of both sexes. The parasite is of potential use as a controlling agent of this mealybug in West and Central Africa where it is established as a pest of cassava.

Eurycoccus cuniculorum sp. n. and E. tamariscus sp. n., are described from Pakistan. They were collected on species of Tamarix during a survey of insect pests by the Commonwealth Institute of Biological Control for possible natural enemies of Tamarix spp. that have become undesirable plants in the USA. The mealybugs live under the bark or in tunnels caused by other organisms and both species have unusual characters in the positions of the thoracic spiracles.

Descriptions, illustrations and measurements of the egg, the five nymphal instars and the adult of Amblypelta theobromae Brown, a serious pest of cocoa on the mainland of Papua New Guinea, are presented. A key for the separation of the nymphal instars is provided.