﻿HYBRIDS OF THE GENUS OPORABIA. 3 



region. From this fact alone it is easy to see that, in all 

 probability, 0. autumnata is the older form, a statement that is 

 confirmed by the fact that both ova and larvae of 0. dilutata are 

 more specialised, and its genitalia slightly more complex, the 

 valves possessing a strong spine. 



Owing to the attraction which difficult species possess for 

 those of an enquiring nature, attempts to hybridise these two 

 forms by other observers were made several years ago, but 

 proved unsuccessful. Becoming interested in these unsuccessful 

 attempts, and having gained experience in my very successful 

 experiments with the Bistoninae, I determined to repeat the 

 trials. For that purpose I reared a large number of imagines 

 from local ova of autumnata, but my first attempt proved futile, 

 for the microgene pinivoraria was chosen, and this emerges in 

 mid-September and is quite over by the end of the month ; 

 dilutata vera does not emerge until mid-October. The experi- 

 ments had to be postponed until the following year, when use 

 was made of imagines of the form alticolaria, which emerge over 

 a period extending from late September to late October. Retard- 

 ing or forcing has little or no effect in this genus, and one must 

 use microgenes emerging at; the same time. These preparations 

 were not in vain, as, when the first dilutata emerged in October, 

 1912, I had both sexes of alticolaria already in the cages. The 

 dilutata males, as they emerged, were placed with alticolaria 

 females, and vice versa. Successful pairings were secured at 

 once ; these differed, in the case of dilutata $ x autumnata 2 

 crossing, from normal pairings of the two parent species, 

 inasmuch as, instead of separating after a few minutes, the 

 pairs remained in cop. for twenty-four hours. Eggs, however, 

 were freely laid as a result of both cross-pairings during the 

 second night, and very soon displayed their fertility by turning 

 salmon-pink in the case of ova laid by autumnata, and dull ruby 

 red in the reverse case. These ova remained unhatched until 

 the following April, when practically every egg yielded a 

 larva. 



The larvse were offered hawthorn, and this food they adopted. 

 In habit the larva resembled, in both cases, those of autumnata, 

 for they ate ravenously and stuck close to their food, displaying 

 none of the tendency of dilutata larvse to wander. Description 

 of the larvse is quite unnecessary, because they bore every 

 character of dilutata vera larva superimposed on those of 

 alticolaria. In none of my numerous experiments have I had 

 such a perfect combination. 



Pupation took place in early June, and I naturally expected 

 the pupte to sestivate for four months like those of their parents, 

 but such was not to be the case with all ; sixteen days after pupa- 

 tion a female imago emerged in the dilutata <? x autumnata ? 

 pot. This was quickly followed by a number of others, all 



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