1880.] 127 



PARTHENOGENESIS IN THE COLEOPTEBA* 

 BY J. A. OSBORNE, M.D. 



In the "concluding remarks " in his treatise on " Wahre Parthe- 

 nogenesis " (1856), von Siebold says, "Es ist daher jetzt Aufgabe der 

 Entomologen, nach weiteren Beispielen von Parthenogenesis in der 

 Insektenwelt zu forschen;" and on the last page (237) of his "Beitrage 

 zur Parthenogenesis," published fifteen years Jater, he expresses the 

 conviction that many facts relating to this phenomenon are still to be 

 discovered. The instances of true parthenogenesis discussed or 

 referred to in these two works relate to insects of the Orders of 

 Hymenoptera and Lepidoptera, and to some crustaceans, including 

 viviparous agamogenesis, however, as parthenogenetic, the orders 

 Hemiptera and Diptera also furnish examples of this mode of repro- 

 duction ; and for its occurrence in at least one genus of the Trichoptera 

 I have the authority of Mr. E.McLachlan, E.B.S.f The possibility of 

 parthenogenetic reproduction in the CoJeoptera rests only, so far as I 

 am aware — see "Comparative Embryology," by F. M. Balfour, vol. i, 

 p. 64 — on the single instance communicated by me to this journal last 

 year (Nature, vol. xx, p. 430), and this being so, it seemed desirable to 

 make sure of this point by further research during the season now 

 almost past. Accordingly, I have this year kept a considerable number 

 of females of Gastrophysa raphani, laying unimpregnated eggs, and 

 with results which have not only confirmed the previous experience, 

 but much extended it, as I am at present in possession of a living beetle 

 reared from a parthenogenetic ovum. "With your permission I shall 

 now endeavour as briefly as possible to give those circumstantial details 

 without which a bald statement of results would not carry with it a 

 rational conviction of the accuracy of my observations. 



Erom beetles gathered in the beginning of last April I had a batch 

 of eggs on the 7th, which hatched out on the 2 1st of the same month, 

 and on May 13th — 15th yielded about thirty pupae, which were 

 immediately put into separate vessels. On the 20th — 22nd appeared 

 the imagines, of which ten subsequently turned out to be females, and 

 were placed together in pots, but not before the greatly enlarged 

 abdomen had given unmistakable evidence of their sex. The first 

 eggs, three batches, were laid on June 2nd (so completing the cycle, 

 from egg to egg, in fifty-six days). On the 12th of the month I found 



* Re-printed from "Nature," Vol. xxii, pp. 509, 510. 



t I fear Dr. Osborne has somewhat misunderstood some remarks of mine in a letter to him. 

 I am very strongly disposed to believe that parthenogenesis exists in certain species of the genus 

 Apatania in Trichoptera, but it is not proved. All we know is that although the females occur in 

 abundance, no male has yet been discovered. This particularly applies to A. rnnliebris and A. 

 arctica.—R. McLachlan. 



