Queries and Answers, 105 



its supposed use ; or if only accidental. Fig. 38. is a front 

 view of the eye magnified. «, The transparent cornea, 

 through which is seen the numerous lenses ; b, the margin 

 of the eye j c, an attachment, round, and thicker than any 

 other part, the base of which is somewhat spread upon the 

 surface of the cornea ; d is about three times longer than 

 c, but about half as thick; e is a sort of knob attached 

 to the end, and half as thick again as d. Fig. 39. is a 

 side view of the same eye. — D. N. Worksop, July 20, 

 1831. 



Microgdster glomerdtus, — We have had the pleasure to insert several 

 previous contributions to the history of this interesting little insect. That 

 by T. H., Vol. III. p. 50 — 52., with its figures, is rich in information re- 

 specting it ; but that gentleman had the misfortune to apply to the insect 

 the name of /chneumon or Platygaster ovulorum, which, of right, belongs 

 to a distinct species. Out of this misnomer arose, however, the benefit of 

 Mr.Westwood's scientific correction in Vol. III. p. 452., where, in connection 

 with that correction, valuable information is supplied on the /chneumonidas 

 generally. Mr. Morgan asks a question about this insect in Vol. III. p. 476. 

 under the title of " Flies and Butterflies ;" and Mr. Westwood replies to 

 this question in Vol. IV. p. 95. under the title of" Mr. Morgan's Worms." 

 To the same question our esteemed correspondent Mr. Bree also supplied 

 an answer, which, by an almost unpardonable mistake, we inserted in the 

 Gardener's Afagazine, vol. vii. p. 121. We know no better mode of 

 correcting our error than to reprint the article into this Magazine, that the 

 communication may follow in its due order, and be seen by such of our 

 readers as are not accustomed to peruse both works. 



Greenish black-marked Caterpillars on Cabbages. — In your last Number 

 (Vol. III. p. 477.) Mr. Thomas Morgan puts a question concerning a 

 " number of minute eggs" enveloped in a silky substance, and apparently 

 produced by " the greenish and black-marked worms found on cabbages." 

 Presuming that by "the worms" described he means the caterpillars of 

 Pontia brassicae (large garden white butterfly), which I have no doubt are 

 what he alludes to, I feel no hesitation in referring " the minute eggs" to 

 the pupae of a well-known small parasite called Microgaster glomeratus 

 (/chneumon glomeratus of Linnaeus), of whose operations I extract the 

 following account from Insect Transformations y p. 61, 62., where a figure 

 of the insect will be found in its diflerent states, together with that of the 

 caterpillar on which it preys. The insect has also already been figured in 

 your Magazine (Vol. lit. p; 52.) under the erroneous name of Platygaster 

 ovulorum as shown at p. 452. of the same volume. " It must have occurred 

 to the least attentive observers of the very common cabbage caterpillar (Pon- 

 tic brassicae), that when it ceases to feed, and leaves its native cabbage to 

 creep up walls and palings, it is often transformed into a group of little balls 

 of silk, of a fine texture, and a beautiful canary-yellow colour ; from each of 

 which there issues, in process of time, a small four-winged fly (Micro- 

 gaster glomeratus Spinola), of a black colourj except the legs, which are 

 yellow. By breeding these flies in a state of confinement, and introducing 

 to them some cabbage eaterpillars, their proceedings in depositing their 

 eggs may be observed. We have more than once seen one of these little 

 flies select a caterpillar, and perch upon its back, holding her ovipositor 

 ready brandished to plunge between the rings, which she seems to prefer. 

 When she has thus begun laying her eggs, she does not readily take alarm ; 

 but, as Reaumur justly remarks, will permit an observer to approach her 

 with a magnifying glass of a very short focus. Having deposited one egg, 

 she withdraws her ovipositor, and again plunges it with another egg into 

 a different part of the body of the caterpillar, till she has laid in all about 

 thirty eggs. It is not a little remarkable that the poor caterpillar, whose 



