274 



HARDWICKE'S SCIENCE-GOSSIP. 



the end of June, and disappearing with the dying 

 of the leaves, the latter part of July. 



The second species is a still more invariable living 

 accompaniment of both kinds of Sarracenia men- 

 tioned. By the time the whitish efilorescence shows 

 around the mouth of the pitcher, the moist and 

 macerated insect-remains at the bottom will be 

 found to almost invariably contain a single whitish, 

 legless, grub or " gentle," about as large round as 

 a goose-quill, tapering to the retractile head, which 

 is furnished with two curved, black, sharp hooks, 

 truncated and concave at the posterior end of the 

 body. 



This worm riots in the putrid insect-remains, and 

 when fed upon them to repletion bores through the 

 leaf just above the petiole and burrows into the 

 ground. Here it contracts to the pupa state, and 

 in a few days issues as a large two-winged fly, which 

 I have described in the Transactions of the St. Louis 

 Academy of Science as Sarcophaga Sarracenice, — the 

 Sarracenia Tlesh-fly. 



The immense prolificacy of the Flesh-flies, and 

 the fact that the young are hatched in the ovaries 

 of tlie parent before they are deposited by her on 

 tainted meat and other decomposing or strong- 

 smelling substances, have long been known to en- 

 tomologists, as has also the rapid development of 

 the species. The viviparous habit among the 

 Muscidse is far more common than is generally sup- 

 posed, and I have even known it to occur with the 

 common house-fly, which normally lays eggs. It is 

 also possessed by some ffistridse, as I have shown 

 in treating of CEdrus ovis, the Sheep Bot-fly. 



But the propensity of the larvae for killing one 

 another and their ability to adapt themselves to 

 difi'erent conditions of food-supply are not sufficiently 

 appreciated. I have ; long known, from exten- 

 sive rearing of parasitic Tachiuidse, that when, as is 

 often the case, a half-dozen or more eggs are 

 fastened to some caterpillar victim only large 

 enough to noiirish one to maturity, they all hatch 

 and commence upon their common prey, but that 

 the weaker eventually succumb to the strongest and 

 oldest one, which finds the juices of his less fortu- 

 nate brethren as much to his taste as those of the 

 victimized caterpillar. Or, again, that where the 

 food-supply is limited in quantity, as it often is and 

 must be with insects whose larva; are parasitic or 

 sarcophagous, such larvae have a far greater power 

 of adapting themselves to the conditions in which 

 they find themselves placed, than have herbivorous 

 species under like circumstances. 



Both these characteristics are strongly illustrated 

 in Sarcophaga Sarracenia. Several larvee, and often 

 upwards of a dozen, are generally dropped by the 

 parent fly within the pitcher; yet a fratricidal 

 warfare is waged until usually but one matures, even 

 where there appears macerated food enough for 

 several. And if the Xanthoptera larva closes up 



the mouth of the pitcher ere a sufficient supply of 

 insects has been captured to properly nourish it, 

 this Sarcophaga larva will nevertheless undergo its 

 transformations, though it sometimes has not 

 strength enough to bore its way out, and the 

 diminutive fly escapes from the puparium, only to 

 find itself a prisoner, unless deliverance comes in the 

 rupture or perforation of the pitcher by the Moth 

 larva or by other means. This rupturing of the 

 pitcher does not unfrequently take place, for Dr. 

 Mellichamp writes under date of June 27 as follows : 

 —"Most old leaves now examined — I might almost 

 say all — instead of being bored, seem ripped or torn, 

 as if by violence, apparently from without. You 

 see occasionally shreds of the leaves hanging. 

 Surely the legless larva of Sarcophaga cannot do 

 this! What then— toads, or frogs, or crawfish 

 abounding in these moist, pine lands ? or rather is 

 not the fat maggot the occasion of the visits of the 

 quail which lately I have observed here ? " 



These two insects are the only species of any size 

 that can invade the death-dealing trap with impunity 

 while the leaf is in full vigour, and the only other 

 species which seem at home in the leaf are a minute 

 pale mite belonging apparently to Holothyrus, in the 

 Gamasidai, and which may quite commonly be found 

 crawling within the pitcher ; and a small Lepido- 

 pterous leaf-miner, which I have not succeeded in 

 rearing. There must, however, be a fifih species, 

 which effectually braves the dangers of the bottom 

 of the pit, for the pupa of Sarcophaga is sometimes- 

 crowded with a little chalcid parasite, the parent of 

 which must have sought her victim while it was 

 rioting there, as a larva. 



But all other insects, so far as we know, tumble 

 into the tube and there meet their death. The moth 

 is doubtless assisted in walking within the tube by 

 the spurs on the legs which it, in common with 

 most other moths, possesses ; while the Flesh-fly 

 manages to hold its own by its widely extended legs 

 and stout bristles. Dr. Mellichamp says that when 

 disturbed it buzzes violently about, just as if an 

 animated sheep-bur had fallen into the tube— not 

 apt to go down, because it will hitch and stick, and 

 finally, by main force, it generally emerges, but, once 

 in a while, also succumbs. 



Two questions very naturally present themselves 

 here :— (1) What gives the Flesh-fly more secure 

 foothold on the slippery pubescence than the common, 

 house-fly exhibits ? (2) What enables the larva of 

 the Flesh-fly to withstand the solvent property of 

 the fluid which destroys so many other insects? I 

 can only ofl'er, in answer, the following suggestions : 

 the last joint of the tarsus of the common house-fly 

 has two movable, sharp-pointed claws, and a pair 

 of pads or " pulvilli." These pads were formerly- 

 supposed to operate as suckers, and all sorts of 

 sensational accounts of this wonderful sucker have 

 been given by popular writers, who forget that 



