Miscellaneous. 311 



its Dipterous parasite, and of recogniziug the physiological conse- 

 quences resulting from this likeness in acts of the same nature 

 which both have to perform. 



In order to bring out the originality of the biological phenomena 

 of which I have been witness it will be well to give a brief historical 

 sketch, Benj. D. Walsh, in 1864, was the first to discover, in the 

 United States, that certain Diptera of the family Eombylida3 

 {Systro_pus) were parasitic upon Limacodid Lepidoptera. This obser- 

 vation, superficial though it was, is none the less interesting, 

 inasmuch as at that time the Bombylidte were regarded as exclu- 

 sively parasites of Hymenoptera ; we know nowadays that their field 

 of action is far more extended. "VVestwood (1870), having received 

 from Natal Limacodid cocoons from which ?l Systropus had emerged, 

 was able to verify the correctness of the preceding observation and 

 complete it with the assistance of figures. He remarked that the 

 head of the nymph exhibited " a strong conical frontal projection, 

 by means of which it is without doubt capable of pushing back the 

 operculum at the extremity of the Lepidopterous cocoon " ; having 

 before him, however, dried specimens, he had no suspicion of the 

 ingenious process employed to enable the nymph to quit its prison. 

 Carlos Eerg simply mentions (1878) that Systrojjus frequently issued 

 from the cocoons of Limacodid Lepidoptera {Sibine, nee Streblota, 

 de Berg, bonaerensis. Berg). Lastly, l)r. T. A. Chapman (1902), 

 having received from La Plata the cocoon of an unknown Limacodid, 

 accompanied by the exuviae of a /Systrojms, also unlcnoivn, supposed, 

 after an examination of the head of the Lepidopterous chrysalis and 

 that of the nymph of the Dipterous parasite, and after comparison 

 with the figures given by Westwood, that both were capable, not, as 

 the English author supposed, of lifting up a pre- existent operculum, 

 but of making for themselves the opening by which the adult insects 

 escaped. These were nothing more than conjectures ; observations 

 on the living subject could alone determine whether they had any 

 foundation in fact. 



This being the question, the following observations were made by 

 the author. In the autumn, that is to say in the month of June, 

 the cocoons of Sibine bonaerensis are not infrequent on fruit-trees, 

 and especially pear-trees, in the gardens of country houses (quintas) 

 near Buenos Ayres ; if the cocoons are opened during the winter 

 months two conditions present themselves : in the first the Lepi- 

 dopterous caterpillar is found contracted and immobile, and so it will 

 remain until the fine weather, when it will be suddenly transformed 

 into a chrysalis, the imago emerging eight to ten days later; in 

 the second case its place is taken by the larva of the Dipterous 

 parasite, also contracted and immobile, remaining in this state also 

 until the hot season, when it is changed into a nymph, becoming 

 adult a few days later. The larvoe of the host and of the parasite 

 are thus both in that state of somnolence which I have called 

 " Injpnodie " ; on the other hand, the chrysalis of the former and 

 the nymph of the latter are both active and capable of developing 



