APPENDIX C.
Severalof the Teneriffe moths, although similar to English and European species, assume rather a darker insular form. The Triphæna Pronuba, Calocampa Exoleta and Asopia Farinalis are examples of this. The Sterrha Sacraria is also met with marked with a much brighter red than in ordinary specimens, and showing great diversity in shade of colour, from red to almost yellow. Anyone wishing to acquire more knowledge on this subject should refer to “Observations on some remarkable Varieties of Sterrha Sacraria, with general notes on Variation in Lepidoptera, by R. M. McLachlan, F.L.S.” Transactions of the Entomological Society of London, Ser. 3, vol. ii, pp. 453-468, pl. 23.
Those who are interested in the subject, and have sufficient time and patience, would probably be wellrepaid for their trouble by the result of experiments in selecting and breeding together insects of the same species which exhibit any slight deviation in their markings and colour. Thus in rearing a number of the Pyrameis Callirhoe several specimens have been observed to emerge from the chrysalis state with bright yellow instead of red markings on the margins of the hind-wings. The white markings on the upper wings also varied somewhat. The Pyrameis family would possibly lend itself freely to the production of new varieties. The Danais Chrysippus is another species of butterfly which presents itself for experiment. By selecting the lighter hind-wing variety, Alcippoides, for breeding, perhaps the Alcippus, which hitherto has not been found in Teneriffe, might be produced. Among the smaller butterflies, the Chrysophanus Phlœas, and the Astrarche var. Aestiva have both shown deviation in colour and markings, but these are much smaller, and consequently more difficult to rear. Moreover, they would not lend such an interest to the subject as the larger specimens.
In the moths, the Deilephila Tithymali caterpillars,if fed on a species of milk-wort, evince a slight variety in colouring and size of moths as compared with those fed on Euphorbia. They must, however, be fed on the plant from the earliest stage, as they only thrive on the food to which they have been accustomed from the first. Some of the earliest specimens are occasionally found on the milk-wort, the eggs having been deposited thereon. Those found in January are more likely to thrive on this food than those met with later on, as the Euphorbia, on which they generally feed, is not in its prime till the early spring.
Great care, patience, and time are required for these most interesting experiments, but the natural advantages of the climate of Teneriffe would greatly facilitate any efforts made, as the variation in temperature is so slight, and consequently the breeding process can be carried on nearly all the year round. Experiments of this nature, which might pleasantly be made by those with whom time might otherwise pass slowly in Teneriffe, would probably prove of distinct value to students of Biology.