524 



wax and oviposit on the fir. This form is CJicrntett cooleyi var, coweni^ 

 Gill. The young hatching from these eggs remain on the Douglas fir 

 until the following spring, when they become stem-mothers. The 

 migrants to the Sitka spruce deposit from 30 to 40 eggs, the young from 

 which probably become the stem-mothers for the new broods on the 

 ^spruce in the following spring. Injury to Douglas fir takes the form of 

 a curling and bending of the needles at the point of attack, but does not 

 appear to affect the health of the tree to any extent. The natural 

 enemies include larvae of Syrphid flies and certain Coccinellids attacking 

 the pupae within the galls, though they do not occur in sufficient 

 numbers to control this pest effectively. 



Treherne (R. C). The Cabbage Maggot — Autumn Development in 

 British Columbia. — 46th Aim. Bept. Entom. Soc. Ontario, 1915, 

 Toronto, 1910. pp. 130-139, 3 tables, 2 charts. [Received 10th 

 October 1916.] 



Three complete and overlapping generations of Chortophila {Phorbia) 

 hrassicae usually occur each year in the vicinity of Agassiz. The 

 observ'ations recorded in this paper were made on and after 1st 

 September and thus deal with the third and perhaps with a partial 

 fourth generation. Collections of puparia were made in order to 

 determine the stage in which the winter was passed. Under both field 

 and laboratory conditions adults emerged freely from the soil during 

 September. In the laboratory the duration of this stage varied from 

 7 to 25 days. Adults emerging between 20th and 27th September and 

 fed on syiup and water lived in some cases until 8th October, when a 

 sudden fall in temperature to 33""" F. occurred. No flies emerged from 

 puparia in the laboratory after 27th September. In the field emergence 

 ^^ntinued until October and adults were active as late as 22nd October. 

 Egg-laying records showed that the number of eggs deposited on 

 cauliflowers in the field far exceeded that on cabbages. Eggs collected 

 between 13th and 26th September and placed in the soil round a plant 

 yielded larvae of from 3 to 4 mm. long by 25th October. These and 

 larvae hatching out later would certainly be able to reach the pupal 

 stage before the approach of very severe weather, which does not 

 usually set in until the end of December or the beginning of January. 



Treherne (R. C). The Cabbage Maggot in British Columbia {PJiorhia 

 hrassicae) ; the Natural Control by Parasites and Predaceous Insects. 

 —4(ith Ami. Bcpt. Entom. Soc. Ontario, 1913, Toronto, 1916, 

 pp. 140-145, 3 tables. [Received 10th October 1916.] 



Oviposition by Chortaphila (Phorbia) hrassicae in the Lower Eraser 

 Valley is continuous from the beginning of April until October. A 

 record of the total number of eggs deposited on certain plants between 

 17th April and 26th October was made, and of these about 2,500 were 

 tested to determine their fertility. Larvae emerged from more than 

 80 per cent. Field records show that the actual number of larvae and 

 pupae present falls considerably below this percentage. This is due to 

 a heaAy mortality among young larvae and to the presence of parasitic 

 and predaceous enemies. The only parasite at present known in the 



