FOREST IMPORTANCE OF MYELOPHILUS MINOR HART. 
223 
As a result of very careful observation and comparison in the woods, I do not 
hesitate to say that piniperda swarms earlier in the spring than minor : on an 
average there may be a month of difference in the appearance of the two species. 
Host Trees. 
In the Continental forest literature M. minor is reported as attacking a number 
of species of pine ; in Scotland I have found it only on Scots pine. M. piniperda is 
also typically a pine species, but I have frequently found it working on felled spruce 
and larch. 
Length of Life of M. minor and the Number of Generations in a Year. 
The old view, championed for example by Eichhoff, was that these forest beetles 
had not only a comparatively short life as adults, but that the newly issued imagos, 
once their external chitinous covering had hardened, were able to proceed at once 
to an efficient copulation followed by egg-laying. This was disproved by von 
Oppen,* Nusslin,! and MacDougall £ for Curculionidae. It has been further dis- 
proved for a number of Scolytid species in a series of papers by Pauly, Nusslin, § 
Knocke,|| and Fuchs.. 1 An excellent summary of results is given by Hagedorn. ## 
From the researches of the four last-named authors, we now ascertain that several, 
indeed a number of Scolytid species do not die after pairing and a fresh egg-laying, 
but can proceed, after a period of renewed feeding, necessary in order to recuperate 
and render their sexual organs once more functional, to a further pairing, followed 
by a second egg-laying and second brood. It has also been satisfactorily demon- 
strated for a number of Scolytid species that the imago on its first appearance from 
the pupal condition is, owing to the unripeness of the sexual organs, unable to 
proceed to an efficient copulation followed by egg-laying, but that a feeding period 
must intervene in order that the reproductive organs may be properly matured. 
In relation, then, to the sexual organs, two periods of feeding have to be distin- 
guished, viz. a feeding preliminary to the first efficient pairing and egg-laying, 
and a renewal of feeding for recuperation purposes that follows the exhaustion due 
to the egg-laying and rearing of the first brood. 
As regards the feeding of the imago necessary to bring the sexual organs to 
* Von Oppen, “Zur Lebensdauer des Hylobius abietis,” in Zeitschr. f. Forst. und Jagdwesen, v ol. xv, 1883, and 
vol. xvii, 1885. 
f Nusslin, “ Uber Generation und Fortplanzung der Pissodesarten,’’ in Forstlich naturvrissenschaftlichen 
Zeitschrift, 1897. 
f MacDougall, “Ueber Biologie und Generation von Pissodes notatus,” in Forstlich naturwissenschaftlichen 
Zeitschrift , part v, 1898. “ The Biology of the Genus Pissodes,” in the Proceedings of the Royal Society of Edinburgh, 
1900. 
§ Nusslin, Leitfaden der Forstinsektenlcunde, 1905 and 1913. 
|| Knocke, “Beitrage zur Generationsfrage der Borkenkafer,” Fortwiss. Gentralblatt, 1900 and 1904. 
TT Fuchs, TJber die Fortplanzungs verhdltnisse der rindenbrutenden Borlcenlcdfer, 1907. 
** Hagedorn, “Fani. Ipidpe,” in Genera Insectorum, 1910. 
