Several of 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 well repaid 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.