20 



Further Notes on Tortrix pronubana, Hb., including its 

 Life History in Britain. 



By Robert Adkin, F.E.S. Read January gt/t, 1908. 



Since the publication of my Notes on the occurrence of Tortrix 

 pronubana in Britain ("Proa," 1906-7, pp. 13 — 17), I have had the 

 opportunity of extending my acquaintance with the species ; and 

 although this has caused me to somewhat modify my views in regard 

 to some of its habits, to which I will refer later, it has fully con- 

 firmed the suggestion that I then made, that the species would prove 

 to be at least double-brooded in this country, in spite of the much 

 more northern position of our islands, as compared with any other 

 of its previously known habitats. It has also enabled me to follow 

 the species through all its stages, from the egg-laying by the parent 

 moth to the emergence of the resultant imago. 



The Spring Brood. — On the evening of May 18th I went to* 

 Eastbourne for the week-end, and at once set to work on the Euo- 

 nymus hedges where I had found the larva; of T. pronubana in the 

 previous autumn. Larvse were not particularly plentiful, and on 

 this, and the two following week-ends that I was able to devote to 

 the search, I secured only some three or four dozen larvae in all, and 

 these evidently included more than one species. Those who have 

 reared Tortrices from collected larva; will appreciate the great simi- 

 larity which exists between many species, and the consequent 

 difficulty in determining a particular species by the appearance of 

 its larva ; the food-plant, or the method of feeding, often proving 

 more reliable as a means. of differentiation. In the present case the 

 food-plant obviously afforded no guide, as the larvse were all collected 

 from one species of shrub ; and as to their method of feeding, where- 

 as those taken in the previous autumn were almost invariably feeding 

 between united leaves, these spring examples were, for the most 

 part, in a single leaf, the edges of which were drawn together. As. 

 to the larvae themselves, none appeared to agree exactly with my 

 recollection of those previously taken ; but, whereas some certainly 

 were not the desired species, others bore a certain family likeness to 

 it, which made it desirable to keep them all and wait the course of 

 events. The result of this method was that on June 10th a male 

 T pronubana emerged, followed by others of both sexes, at irregular 

 intervals, during the next few weeks, thus clearly demonstrating the 

 existence of a spring brood. The following species were also reared, 

 namely, Tortrix podana, T forsterana, T heparana, T. rosana,* 



* Reared from a pupa; probably the larva had strayed from an adjacent 

 rose-bush. 



