ABSTRACT
1. The highest temperature which wireworms could withstand for an indefinite period without becoming paralysed was found to-be between-35 and 36 ° C.
The resistance to high temperature was not influenced by the previous temperature.
2. The resistance of wireworms to low temperature was found to be greatly influenced by the rate at which the temperature was reduced.
When the temperature fell rapidly, all were killed by 6 days’ exposure to – 3°C., and by 4 hr. exposure to –7°C.
The resistance to low temperature was not increased by a previous exposure of 24 hr. at o°C., when the subsequent fall of temperature was rapid.
When the temperature was lowered in small stages, however, the resistance was considerably increased, and a few wireworms survived for at least a day at − 10°C.
3. The published data of soil temperatures suggest that temperatures above 30 ° C. or below about − 1 ° C. are not of regular occurrence in England, and it is concluded that wireworms in England are not normally liable to encounter lethal temperatures..
4. The relationship between the wireworms’ speed of crawling and the temperature was found to be nearly linear between 8 and 25°C.
5. Burrowing activity was uniformly greater at higher than at lower temperatures between 6 and 33°C. Temperature influenced the speed but not the continuity of the activity.
After adaptation had taken place the burrowing activity was almost nil at 6°C.
When subjected to a sudden fall of temperature from 16 to 6 °C., the wire worms’ burrowing activity in the first 2 hr. was significantly greater than it was at the same temperature 16 hr. later.
6. The weight of wheat eaten by wire worms was found to be greatest at 32 ° C., but feeding activity was most continuous at about 18°C. At 7°C. and at 34° C. little feeding took place.
7. No vertical movements in response to gravity were exhibited by the wireworms under any conditions of temperature.
8. When given a choice of temperatures in an alternative-chamber apparatus, the wireworms showed a clear preference for 17°C. as against 11·5 and 21°C. or higher temperatures.
The temperature preference was not found to be influenced to any great extent by the previous perature.
9. The mechanism by which the wireworms reacted at a temperature boundary was of the nature of a ‘shock reaction’, their direction of movement being reversed.
No evidence of a klinokinetic response to change of temperature was obtained from wireworms burrowing in sand.
