In the case of silica, there appears to be a definite variation of SiO2 content with different species. The difference between yellow locusts (6·27 per cent.) and red locusts (14·7 per cent.) is especially marked. It may be attributed to the fact that red locusts are actively feeding, sexually immature adults, and in consequence they consume large amounts of food with a high silica content. The fact that museum specimens of yellow locusts contain a higher percentage of silica than intact yellow specimens indicates that the majority of the silica is not concentrated in the digestive tract. The same appears to apply to the iron content. Copper was found in appreciable quantities in all the insects examined, but no definite conclusion can be drawn from the numerical results, as the variation from batch to batch was too great. The results for manganese are not satisfactory, as in several cases negative evidence was obtained. This is inconsistent with the work of Vinogradov, who obtained conclusive evidence of manganese in insects. In the case of Agonoscelis, however, the manganese content was found to be extraordinarily high (0·47 per cent.), suggesting that it may play a definite physiological part. The presence of a respiratory pigment, pinnaglobin, containing manganese, has been shown in the tropical mussel, but there is as yet no evidence for the presence of this pigment in the insect world.

It is impossible, however, to draw any such conclusions from ash analysis results of entire insects only, and systematic analyses of the blood of numerous species will be necessary to establish the presence of the metals iron, copper and manganese, in their respiratory pigments.

Definite evidence of nickel (in almost negligible amounts) was shown by the large-scale analysis, but apart from this no element was detected which had not been previously reported.

The larvae of Uranotaenia ornata, Theo., are commonly found in pineapple plants in the neighbourhood of Lagos, Nigeria, and invariably in company with Harpagomyia larvae.

Tomaspis saccharina, Dist., is a Cercopid bug which infests the cane-fields of Trinidad in vast numbers during the wet months of the year. Corresponding with the successive generations, there are three, and sometimes four nights or broods of adults, each of which causes severe damage to the cane. This damage, or “ froghopper blight,” as it is locally called, is a result of the feeding activities of the adult on the foliage, and is characterised by a progressive discoloration of the leaves, leading to death of the affected leaf and, in severe cases, to the death of the cane. In either event, growth of the plant is more or less severely checked and the adverse effect on yield is usually of a very significant nature.

The following notes deal with a collection of sandflies from Africa sent for identification by Sir Guy Marshall, C.M.G., F.R.S., of the Imperial Institute of Entomology, by Dr. Pontes from Mozambique, by Major W. F. M. Loughnan, R.A.M.C., Mauritius, and with a number of specimens lent to Prof. Adler by the London School of Tropical Medicine. I am indebted to Prof. Adler for placing this material at my disposal.

For a number of years the western grass-stem sawfly, Cephus cinctus, Norton, has been accounted one of the major insect pests of wheat in Western Canada. Originally a grass-feeder, it began to attack wheat about the beginning of the present century, at first only occasionally and at the edges of fields in Manitoba, later much more commonly and with a very wide distribution throughout the wheat-growing areas of Manitoba, Saskatchewan, and Alberta. While this sawfly was confined to native grasses it was held in check by two principal factors (Criddle, 1922) : shortage of grass stalks suitable for oviposition, and parasites. When, however, it began to attack wheat, both of these restraints were evaded. In the first place the wheat fields provided an abundance of host-plants. In the second place, the natural parasites of the sawfly did not move with it into the grain fields—whether they are unaware of the presence of their host in wheat plants or are unable to attack it in that situation is unknown.

In response to the expressed desire of Mr. Arthur Gibson, Dominion Entomologist, to introduce European parasites to aid in controlling the Western Wheat-stem Sawfly, Cephus cinctus, a shipment of 15,000 wheat stubs containing parasitised Cephus pygmaeus was forwarded to Canada from the Farnham House Laboratory, Farnham Royal, Bucks, England, in the early spring of 1930. This stubble was received at the Dominion Parasite Laboratory, Belleville, Ontario, and was there held in cold storage until reshipped to Western Canada, where the parasite, Collyria calcitrator, was to be liberated.

The locust infestation in Nigeria, from December 1929 to April 1931, is studied in relation to the climate and the following preliminary conclusions are made.

1. Humidity, precipitation and wind are the relevant climatic elements. Temperature does not seem of importance.

2. It is considered that the area of dispersal is limited by the humidity factor. With very few exceptions swarms remain where the mean relative humidity (9 a.m., L.M.T.) is not more than 85 per cent. and not less than 40 per cent., while most swarms are found where the humidity is from 60 per cent. to 80 per cent.

3. This humidity belt is similar to the area covered by three main types of vegetation and the swarms move across the belt according to the humidity changes.

4. Movement along the belt is largely caused by the prevailing wind.

5. Breeding does not commence after the dry season until the humidity rises to 60 per cent. and the degree of wetness, calculated from the monthly rainfall, reaches 2. Breeding does not occur if the humidity is above 80 per cent.

6. Through the dry season the adults seem unable to live much more than 22 weeks, and if optimum breeding conditions are not reached within that period death may occur.

7. Breeding towards the end of the rainy season follows some 11 to 15 weeks after the locusts become adult, so long as the humidity is not more than 80 per cent., and high humidity may cause a diapause.

8. Suitable local conditions during the dry season may allow a third breeding season.

These conclusions may be utilised in the following ways :—

1. To delimit the total area likely to be infested.

2. To forecast when the different zones will be infested by flying swarms.

3. To forecast whether and when breeding is likely to occur in each locality.

4. To check whether unidentified swarms were of this species of locust.

5. To test the possibility of one suspected breeding ground having been infested from another.

The writer was engaged on control measures against hopper bands of the Migratory Locust, Locusta migratorioides, R. & F., along the western (Nigerian) shore of Lake Chad from the middle of August to the end of October 1930.