PULVINARIA VIT1S, VAE. RIBESlyE. 61 



eventually almost to black, and is much wrinkled 

 transversely. 



Summarising these observations, we find that there 

 is but one brood in a year. The larvae hatch in June 

 and the early part of July, the first moult taking place 

 from the middle of July onwards ; the second moult is 

 in August, when a sexual difference is first observed. 

 Pupation takes place towards the end of August, the 

 males appearing in September. They then fertilise 

 the females, when the latter moult again for the third 

 time. Hibernation commences shortly afterwards, and 

 the insects remain dormant until the spring. Egg- 

 laying takes place at the end of April and throughout 

 the early part of May. In all probability the periods 

 here set forth may vary slightly according to the 

 season. My observations were made during the years 

 1899-1902, on a colony established on a large plant 

 of Eibes sanguineum trained on a south wall, and in 

 other ways well sheltered from cold winds. The colony 

 was established by attaching to the plant in question 

 a small branch of black currant, tenanted by about 

 twenty females with their ovisacs full of eggs. In due 

 course the larvae hatched and produced several 

 thousand fertile females, but only one male ! Thus the 

 majority of the females w r ere parthenogenetic. In 

 the following year the increase from the first lot of 

 females was enormous, and portions of the food-plant 

 were at times covered by millions of young larvae, 

 thousands of which perished through want of space on 

 the seasoned wood ; here and there a few examples fixed 

 themselves upon the young and tender shoots, or more 

 rarely upon the leaves, but none reached the first moult 

 on the latter, and very few completed a full life on the 

 former. The colony which survived on the seasoned 

 wood practically covered every available portion of it. 



The second generation under observation produced 

 a large number of males, but there was a great pre- 

 ponderance of females. At that period (1900) the 

 colony was in its most flourishing condition, and every 



