Ll. Lloyd 3 



the garden till the end of May when a few adults were seen on Althaea 

 and Philadelpkus. The Station houses were still quite free from the pest 

 and the nearest infested greenhouse was 200 yards away from the garden. 

 These were probably, though not certainly, survivors from the heavy 

 infestation of the previous year. 



Experiments carried out in the winter 1919-20 afford evidence that 

 the insect may survive a mild winter out of doors in small numbers in 

 the Lea Valley. 



An Urtica dioica, heavily infested with all stages of the pest, was 

 enclosed in a capacious muslin sleeve and placed outside on January 15. 

 The adults became gradually reduced in numbers until on April 13 only 

 12 survived and the young foliage held numerous eggs. All the scales 

 on the plant were dead. 



A second nettle plant, heavily infested with all stages, was cleared 

 of adults, enclosed in muslih, and placed outside on February 2. Seven 

 adults emerged between February 13-20, and eight more between 

 March 9 and April 13. On the latter date oviposition was occurring, but 

 there were no intermediate stages between egg and adult. On May 20 

 the plant held a few adults, eggs and first stage larvae only. 



A Lamium was subjected to a massive infestation of adults on 

 January 14; the following day, when it was well covered with eggs, the 

 flies were cleared from it and it was sleeved and placed outside. The eggs 

 commenced to hatch after 87 days on April 10 and continued to do so 

 until May 10, 117 days after oviposition. 



Adults were placed in muslin-covered glass vessels containing moist 

 soil with and without cut foliage and placed in the shade outside in 

 January. It was found that where no foliage was enclosed they died in 

 less than a month, January 15 to February 9 (25 days) being the longest 

 period that one survived. In one case a Lamium leaf was enclosed and 

 this kept curiously green and fresh for nearly three months. Seventeen 

 adults were placed with it on January 15 and lived an average of 36 days, 

 five survived 50 days, and the last one died on April 6, the 82nd day. 



The outside shade temperatures during this period will be found in 

 Table I. Although the winter was a mild one all the insects concerned 

 in these experiments experienced frost and the adult which survived 

 82 days was subjected to frost on 25 nights. It is therefore clear that 

 both the eggs and the adults are able to withstand considerable cold, 

 but that the intermediate stages are less resistant. Both the resistant 

 stages are dependent on living foliage; as the adult, when subjected to 

 the alternate cold of night and warmth of day, requires food, and the 



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