On The Pigmy Mangold Beetle ( Atomaria Linearis Steph.) and Methods for its Control

Summary. 1. An extensive investigation of the Pigmy Mangold Beetle ( Atomaria linearis Steph.) on sugar beet and mangold has been made during the past six years, both in the field and in the laboratory 2. The symptoms of attack are given, together with a brief account of the distribution and life history of the beetle. 3. General field observations of infested areas both in Lincolnshire and Shropshire indicate that epidemics of the Pigmy Mangold Beetle in sugar‐beet and mangold crops only occur under certain conditions, of which continuous cropping of the land with susceptible plants is usually considered of primary importance. 4. It is found that environmental factors have a marked influence on the relative susceptibility of sugar‐beet and mangold crops to serious injury by the beetle. Evidence is produced to show that many of these factors are under the direct command of the grower and their significance on control measures discussed. 5. Field experiments on control of the pest show that, of the treatments tested, the use of phenol and magnesium sulphate at the rate of 1 and 5 per cent. respectively, as a seed steep is the most effective. 6. There is reason to believe that the common practice on the Continent and in certain districts in this country of sowing crude naphthalene with sugar beet seed as a deterrent against the Pigmy Mangold Beetle results in serious damage to germination. 7. Different varieties of sugar beet vary in the degree to which they are liable to infestation but the differences are generally small and unimportant. Mangolds, as a rule, are more resistant than sugar beet. 8. In addition to mangold and sugar beet, the beetle is recorded for the first time in Great Britain on garden beet and White Goosefoot ( Chenopodium album ). Some evidence is presented to show that a rotation of crops as means of control of the beetle may be ineffective in areas where White Goosefoot prevails.