OF CERTAIN CHALCIDID^E AND ICHNEUMONIDjE. 71 



PART II. ICHNEUMONIM. 



Read May 1, 1849. 



Paniscus virgatus, Fourc. 



The parasites of the genus Paniscus, and their affinities Ophion, which are some of the 

 most active and percipient of insects in their perfect state, are examples of one of the 

 very lowest forms of life as larvae, as well as of one of the most curious modes of nutrition. 

 In the earlier stages of growth they more resemble cotyledonous vegetables, in general 

 appearance, than animal organisms which are destined to become some of the most perfect, 

 and most active of their Class. I have traced Paniscus virgatus from the bursting of its 

 egg to its assumption of the imago state, and have watched its growth and the formation 

 of its tissues. 



The earliest notice I am acquainted with on the habits of an insect of this family is 

 of Ophion luteum, by Goedart*, who found five specimens of the imago produced on 

 the 29th of June from the hard cocoon formed in September of the previous year, by 

 the larva of Cerura vmula, L. Bonnet f afterwards, as quoted by DeGeer J, made some 

 observations on the singular economy of this insect. He remarked that the eggs of Ophion 

 are attached to the outside of the body of the caterpillar of the Puss-moth, by a short 

 pedicle or footstalk inserted into the skin, and that the parasite when hatched is nourished 

 on the outside of the body, still attached to its shell and pedicle like a vegetable growth. 

 DeGeer § found the same insect on the Puss-moth larva, and ascertained that several indi- 

 viduals subsist on the same caterpillar, which dies of exhaustion after it has formed its 

 hard wooden cocoon. More recently the eggs of this genus have been the subjects of a 

 memoir by Dr. Hartig, as mentioned by Mr. Westwood ||, but this memoir I have not yet 

 seen. I do not pretend, therefore, to claim entire originality for the few observations which 

 I have made on Paniscus, but merely to state what I have myself observed, in accordance 

 with the views I have proposed. 



On the 26th of September, 1847, I found many nearly full-grown larva? of the Broom- 

 moth, Mamestra pisi (fig. 13), feeding on that plant in the hot sunshine. On the following 

 day I detected a number of little shining black-looking bodies (a) on one of these larvae, 

 attached to different parts of its three thoracic segments. On examining these bodies more 

 closely, I found to my surprise that they were black shining eggs (a), inserted at one end 

 into the skin of the caterpillar. These eggs were somewhat oval, or rather pear-shaped, 

 the attenuated footstalk being lodged under the skin. There were eight thus attached. 

 But what fixed my attention closely was, that most of the eggs had already burst, or were 

 in the act of bursting longitudinally (14 c), precisely as I have formerly seen and described 

 in the eggs of the Iulidce %. Each egg had divided in the middle line, at its anterior ex- 

 tremity, and the two halves of the shell were separating like the cotyledons of the seeds of 



* Metamorphoses Naturelles, 12mo, torn. ii. p. 162. pi. 37. A la Haye, 1700. 



t Memoires de l'Academie des Sciences de Paris. % Memoires, torn. ii. p. ii. page 851. 



§ Ibid. p. 852, 853. || Introduction, &c, vol. ii. p. 146. ^ Phil. Trans. 1841. 



