A. A. Girault and G. E. Sanders.
The Chalcidoid Parasites of the Common House or Typhoid Fly (Musca Domestica Linn.) and its Allies.
Psyche 17(4):145-160, 1910.

This article at Hindawi Publishing: https://doi.org/10.1155/1910/82048
CEC's scan of this article: http://psyche.entclub.org/pdf/17/17-145.pdf, 1468K
This landing page: http://psyche.entclub.org/17/17-145.html

The following unprocessed text is extracted automatically from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.

Oirault and Sanders - Chalcidoid Parasites THE CHALCIDOID PARASITES OF THE COMMON HOUSE OR TYPHOID FLY (MUSCA DOMESTICA LINN.)
AND ITS ALL1ES.l
111.
DESCRIPTION OF A NEW NORTH AMERICAN GENUS AND SPE- CIES OF THE FAMILY PTEROMALIDAE FROM ILLINOIS, PARASITIC OTES.
ON Musca domestics Linn., WITH BIOLOGICAL N The University of Illinois.
The type species of this new and important genus of the pteroma- line tribe Eutelini, was in point of numbers, third among the chal- cidoid parasites reared by us during the investigations of the common house fly, during the latter part of the season of 1908, it being less numerous than species of Spalangia and the parasite Nasonia brevi- cornis Ashm. Unlike the latter, however, it was not reared inde- pendently or from a number of hosts, but nearly always occurred in connection with some one of the species of Spalangia and we were inclined to believe, though the evidence was lacking, that it usually attacked that genus, and hence is a secondary parasite of the typhoid fly, though its role may also be that of a primary parasite. A fact which contributed to our belief of its secondary role is the general likeness which it exhibits to Spalangia, a not uncommon thing between host and parasite or host and inquiline, though by no means the rule. But we have no evidence whatever to show that this is the case and are forced to the conclusion that the type species of the genus is a primary parasite in every sense. In this third paper of this series, the genus is described and con- sidered in detail and such biological facts as we were able to observe concerning it are also given. This genus, Spalangia and Pachycre- poideus dubius Ashm., already considered, are the principal primary parasites of the house fly, the species of Spalangia being the most numerous and common of the three genera. They will be considered in a paper to follow.
1 Continued from Val. XVII., p. 117.




================================================================================

Psyche
[August
Muscidifurax gen. nov.
Type: M. raptor sp. nov.
Female.
Normal in stature and aspect for the tribe. The general aspect of Tritneptis Girault, 1908, and of Coelopisthia suborbicularis Prov. (Ashm.) ; moderate in size, the head rounded and prominent; submetallic, black.
Head (cephalic aspect) subcircular, moderate in size, the line of the vertex, however, somewhat flattened, slightly bi-lobed, the facial (mesal) impression containing the scapes distinct, moderately deep, but gentle, mod- erately defined and narrow, its lateral margins obtuse, the scrobes sub- obsolete dorsad, distinct near the bulbs, the latter separated; face broad, the clypeus sub-hemispherical, its surface not impressed below the face, but with close, fine, longitudinal, converging strias, its sutures obsolete, its apical (ventral) margin truncate but laterad, on each side of the comparatively broad entire mesal portion of the margin near the lateral termination of the sclerite is a small subacute notch or incision; (lateral aspect) head distinctly bulged or convex below (ventrad) its middle, form- ing in the cephalic aspect, a rounded, convex facial prominence just ven- trad of the insertion of the antennae; head widest just ventrad of the ventral ends of the eyes and then ventrad of the insertion of the antennae obliquely truncate (cephalo-caudad), the line of the face sloping gently from the vertex to the antenna1 insertions and then abruptly, obtusely changing angle and nearly truncately cut off; obovate; eyes elliptical-ovate, about a fourth longer than the genae, practically naked, but bearing sparse, very minute, erect hairs; head with no acute margins; genal sulcus obso- lete. (Dorsal aspect) head somewhat wider than the greatest width of the thorax, about three times wider than long at the vertex, the latter slightly narrowed at the meson, but rounded and slightly convex at its apex at the ocelli, the occipital margin concave, narrowly rounded ; the cephalic margin of the vertex obscure, subacute; the cephalic ocelli circular, larger than the ovate lateral ones, all in a flat or obtuse triangle in the center of the vertex, distant from the eyes, the lateral ocelli about twice the distance from the eye margins on each side as they are from the cephalic ocellus, and a little less than that distance from each other than each is from the cephalic ocellus, the group near the obscure cephalic margin of the vertex; visible margin of the eyes convex, entire; eyes widely separated. Antennae inserted about two-thirds of the way down to the clypeus, below the middle of the face and about on an imaginary line drawn between the ventral ends of the eyes, or slightly ventrad of it, the scapes long and slender, 1 Muscidae and furaa;, inclined to steal.



================================================================================

19101 Girault and Sanders - Chalcidoid Parasites 147 diverging and dorsad extending to the apex of the vertex, the flagellum long and cylindrical, slightly thickening distad; antennae 13-jointed- scape, pedicel, 1 ring-joint, 7-jointed funicle and 3-jointed club; pedicel longer than the first funicle joint, the first and second joints of the funicle longest, the first joint the shorter of the two (Fig. 2). Mandibles 3- (left) and 4-dentate (right) (Fig. 1).
Pronotum distinct, narrow, transverse mesially, widening laterad, the lateral wings being cuneate, mesially not longer than a fourth of the length of the mesoscutum; thorax flatly convex; parapsidal furrows dis- tinct, incomplete, inconspicuous, extending about one-half the length of the scutum, from the cephalic margin; axillae widely separated; mesoscutum elliptical in outline, both the cephalic and caudal margin being broadly convex, the caudal margin nearly straight between the axillae and im- Museidif urccx raptor sp. nov.
Fig. 1. Mandibles. Fig. 2. Antenna of female. Fig. 3. Fore wing of fe- male (ciliation omitted). Fig. 4. Antenna of male. All enlarged; pubescence indicated only, not exact.
Original.
pressed; scutellum with no transverse grooved line cephalad of the apex, but in its disk a few obscure, large punctures similar to those on the heads of many encyrtine genera, its apex broadly convex; mesopostscutellum nar- row, following the outlines of the scutellum, its cephalic and caudal margins ridged or carinate; metathoracic spiracle moderately large, elliptical-oval, oblique in position and nearly its own length from either the mesopost- scutellum or the lateral carina; median and lateral carinse of the meta- thorax complete; median carina of the metathorax divided before base, each division proceeding latero-caudad to meet the lateral carinae; the latter broken at caudal third; spiracular sulcus short, obscure. The whole of the head and thorax densely reticulated, amounting to punctation, the metathorax more coarse, punctate and rugose; abdomen finely, delicately reticulated, polished, the cox= finely reticulated, nearly smooth.



================================================================================

[August
Abdomen sessile, (lateral aspect) conic-ovate, concave dorsad longi- tudindy, convex or ridged along the meson ventrad and pointed caudad, with the tip of the ovipositor exposed, not compressed, shbdepressed, as long as the head and thorax combined: (dorsal aspect) abdomen ovate, ending in a sharp point, widest at about the apex of the third segment, the second segment longest, occupying a fourth of the surface, segment 3 next longest, excepting 7 and 8, a third shorter, segments 4 and 5 subequal, slightly shorter than segment 3; the sutures between segments 3 and 3 ob- scure; segment 6 subequal to 3 but distinctly narrower, segment 1 triangu- lar with the apex of the triangle caudad, at the meson three-fourths the length of segment 2; segment 8 pointed conical, as long as segment 6, the point of the ovipositor protruding fromit slightly; segments 7 and 8 pubescent. Abdomen somewhat variable in shape, sometimes slightly triangularly produced ventrad at base.
Legs normal, the anterior and posterior femora with their caudal mar- gins convexed in the middle, but not conspicuously or abnormally so, the tibia1 spurs all single, the cephalic ones largest, curved, notched at the apex; caudal tibial spurs not half as long as the slender proximal tarsal joint, which is longest, the fourth caudal tarsal joint as usual, shortest, the third nearly as short as the fourth, the second about half as long as the first and longer than the fifth. Caudal cox= largest, their lateral aspect flat, the intermediate coxae by far smallest. The cephalic cox= subconical. Fore wings nomai, widest at a point opposite th: stignaal knob, usually dilate in the disk, the apex rounded; submarginal vein slender, its whole length gently concavely curved, slightly enlarging as it nears the marginal vein, about a third longer than the latter; marginal vein broadened, clavate, its base twice the width of the postmarginal vein, gradually narrowing distad, dark, nearly twice the length of the postmar@nal and stigma1 veins; the latter two veins, slender, short, subequal in length, the post- marginal vein slightly longer, the angle between them about 45O; the stigma1 vein straight, bearing a small ovate knob with an uncus proceeding from its cephalo-distal margin near apex. Marginal cilia absent, except- ing along the venation and distad along the caudal margin where they dis- - appear as the apex of the wing is neared; short. (Fig. 3). Posterior wings widest before their middle; the cephalic margin of the wing is neariy straight* obliquing distad; the caudal margin broadly con- broa3Iy emareinate towards base, sloping distad but the apex obtuse; Tical cilia dense, but delicate and minute; marginal cilia moderate in length on the caudal marfin. Venation usual; about 33 hoolclets. Maxillary palpi &jointed, the last joint much the longest, cylindrical oval. Labial palpi %jointed.
MahÌÔTh same,
Byes smaller, about the length of the genffi, ovate; antennae more slender, filiform, more noticeably hairy, pilose, mow loosely jointed, the distal funicle joints subpedunculate; IAijointed, with two ring- joints and a 4-jointed dab: the funide bat 6-jointed, the first funicle joint very long, cylindrical, narrowed in the middle, the joints shortening distad,



================================================================================

19101 Girmilt and Sanders - Chalcidoid Parasites 149 the pedicel much shorter than the first funicle joint; apical joint spur-like (Fig. 4). Abdomen depressed, ovate, sessile, not as long as the thorax, the genitalia exserted in death; mandibles and other characters as in the female. A genus closely allied to Eutelus Walker and Platymesopus West- wood, from both of which it is separated by the single ring-joint of the female antennae, as well as more general characters. The type and sole species of this genus, as our records given beyond will show, is an important primary parasite of the common house fly, of solitary habit and external, attacking the host in the pupariuin stage but not penetrating the body of the inclosed pupa, its larva obtaining nourishment through the body-wall of its host by means of absorption. Its host relations are therefore very similar to those of Spalangia - those species attacking Musca -in that it is mostly confined to a single host and is external and solitary in habit. But seemingly unlike the species of Spalangia, which we consider in another paper, this parasite also occasionally attacks other host genera, we having reared it rarely from the puparia of both the screw-worm fly, Cfirysomyia macellaria (Fabr.) and also Phormia regina (Meig.) ; from the latter in the laboratory as well as in nature. Rarely, it was also reared from the larva of both of these flies.
We have found this genus in what is practically a single locality in Illinois; in the two adjoining towns of Champaign and Urbana. In that locality it is common. Other portions of the state have not, of course, been explored in reference to it and we have no knowledge concerning its distribution in the United States. Muscidifurax raptor sp. nov.
Female. Length variable; maximum length, 3.60 mm.; minimum length, 1.80 mm.; average length, 9.34s mm.; range, 0.80 mm.; mode, 2.30 mm. General color black, with slight senescence, subcorvinus; flagellum deep black, appearing slightly greyish from the pubescence; the abdomen with some brownish, at base ventrad on segment 3, a yellowish-brown spot on each side of the meson, often contiguous forming a transverse yellowish-



================================================================================

brown band3 and with traces of yellowkh-bmwn dorsad at base of the 3econd abdominal segment; the kga, excepting the CO~CO~O~OUS black ma, and the scape fu~cous, the femora dorsad bd bierad variable, mudfy with black id^, especidly in the cwdd and cephalic femora; scqe darker doraad, pedicel and rinpjohts with some yellowish; exposed portions of the mandi5Ies black or dark fuams; palpi dusky; teguk black; tarsi slightly paler, their distal joint bkk; wings snbhpline, the marginal vein conspicuous, black3 especially proximad, the remahing venation dusky with some ydlowish Eyes dark garnet, with severd distal black spots; omUi pinJ&h, inconspimow. Venturn concolorous, except as noted in the abdomen.
hbeswnce of body moderately close, inconspicuous. Abdomen polished. FIqeUum moderately densely pubescmL the hairs short and closely applies; stape cylhdricd, narrowing somewhat distd, equal in length3 nearly, to the pedicel, rinpjoint and 3 proximal funicle joints combjned; p&?d long-obconi~ ih proximal end 6Eghffy curved, nearly thrice wider at its apes than at its base, not quite a third of the length of the acape and at least a fourth longer than the first funicle joint and its apex wider than that joint; rin&joint transverse, not M wide as the pedid and about a fifth the length of the first fnnicle joint; first and second funide joints subequal in length, both widening somewhat dishd, the second somewhat wiser than the firs‰â each nearly a third longer than an? of the next five funfcle johta which are subequd in length, each, however, very slightly shorter than the one immedi&ely preceding; the proximal dub joint sub- qud in length md width to the seventh or dktd funicIe joint, the inter- mediate joint sdl, the apical joint small, obtusely conird, hdf the she of the premding.
Funide joints %7 subquadrate. Club as a whole ovat~ not much, if any, wider than the funide, not equal to the united lengths of the three distal funicle joints (joints 5, 6 and T of fdcle). (From 1941 speeimevs.)
Male.
Length variable; 1.343 m,; average, 1.W mm. The same as the female, differing in the ~ u d secondary sexuaI characters pointed out in the generic description, and in color as foUows: The base of the abdomen in the dorsal aspect has a large ~mspimous, rounded, honey-yellow spot, disthct to the naked eye, which is but slighfly hfiicated in the female by the presence of some ~dlowish-brown in that- region; in the same region ventrad, the area iq larger than that in the female and rounded.
The anknn~ have an addikiond ring-joint, om joint hss in the Mcle md a very minute, addition81 fonrth club j0inL which me the un- usual secondary strwtural features.
Flagellum flIifom3 pilose. Scape slender, a fourth longe~ than the pd?cd, ring-joints and first fmicJe joint united; pedicel ohwni~ not long as in the femal~ not by far a half the length of the prdmd funicIe jofnt, subequal in length to the distal (6th) funide joint; ring-joints transverse, the sewnd nearly twice th ske of the first and darker in color; funick joints dl longer than wide, abruptly shortening di*; first fmide



================================================================================

19101 Gi~ault and Sanders - Chakidoid Pusmites 151 joint by far the longest? cylindricaly narrowed or constricted obtusely at the middle, over half the length of the scape? subequal to the club in length? somewhat shorter? with an indication of a petiole or peduncle at its apex and a third longer than the second funicle joint; the latter slightly COR- stricted at proximal third? with a more distinct petiole, the third and fourth funicle joints subequal? each a fourth shorter than the second funicle joint; funicle joints 5 and 6 subequal? each a fourth shortsr than either the third or fourth funicle jointsy and each about half the length of the proximal funicle joint. Petiole or peduncle of joints 3? 4, 5? and 6 of the funicle distinct but not long; funicle joints 5 and 6 acute at their disto-lateral angles? the others less distinctly so; club moderately long, tapering to a point? distinctly shorter than the scape? its proximal joint somewhat shorter than the sixth funicle joint? but nearly as wide, its second joint slightly longer and as wide? its third joint conical? with a narrow truncate apex? not quite as long as the proximal jointy and the fourth distal joint minute, nipple-likey resembling a small conical spur and terminating in a seta. (From 80 specimens.)
Typos: Accession No. 40,250, Illinois State Laboratory of Natural Historyy Urbana? Illinoisy 32 d's, 81 9'sY tagm~untecl. Cotypes-Cotype No. 12,240, United States National Museumy Washing- ton, D. C., 2 d7sY 2 9'sy tagmounted.
Viewed with a hand-lens? the female is uniformly glossy black with a conic-ovate? smoother abdomen which projects to the tip of the wings, marked ventrad near base with brownish-yellowy the wings hyaline with brownish-black marginal? postmarginal and stigma1 veins, the latter dis- tinctly tapering from the thicker base to abex; the leg?å excepting black shining coxz? brownish-yellow marked indistinctly with darker, the lateral aspect of the posterior
femora dark; the antennz black with the scape dark brownish. Eyes and ocelli dark garnet? the former with a discal blackish spot? not distinct; the pubescence indistinct on antennz and body, giving the former an indistinct greyish appearance in direct light. The
sculpture of head and thorax appears distinctly as a very slight, uniform and delicate roughening. The antenna1 flagella are about as long as the thorax. The sculpture appears rougher along the surface of the metanotum. The male appears the same as the female? excepting the shorter? flattened, depressed abdomen containing a moderately large, brownish-yellow spot in the middle near basey and the slenderer? loosely-jointed, softly hairy anten- nal flagella? the pilose pubescence of which is distinct and yellowish grey. When viewed with the naked eye? the parasites look like black gnats with long bodiesy indistinct brown-yellow legs and indistinct clear wings which are folded along the back in the usual position for the Pteromalidz. They appear a third smaller in size than Pteromulus puparum (Linn.) for instance to the naked eye and the sexes cannot be certainly separated with- out enlargement. Through a lens? however? the antenna1 and abdominal characters previously mentioned? together with the exserted genitalia of the male? allow them to be distinguished with readiness. To some extent? to



================================================================================

152 Psyche [August
the naked eye, the species resembles some of the smaller species of Spa- langia and more closelyy Pachycrepoideus dubius Ashmeady but the bodies of the latter are noticeably shorter and more compacty the antenn~ shorter and stouter.
Described from the following 324 specimens) all) with the excep- tion of 50) now in the collection of the Illinois State Laboratory of Natural History and all reared from various house fly puparia) and those of two other Diptera) during the investigations of 1908 in the insectary of the office of the State Entomologist of Illinois at Urbana. Unless otherwise stated all of the specimens are mounted on tags.
(1) Eleven males of the parasite emerged singly on October 17, from 11 puparia of ~Wusca domestics Linnzeus which had been ex- posed in the insectary September 20 and 30; accession No. 40,231 11 d's. (2) On October 24 from the same lot of isolated p~~paria, there were removed 34 d's) 83 9's; accession No. 40,250, 32 d's, 81 9's (2 d's) 2 9's - Cotype No. 12,,240, U. Ss N. M.). (3) 6 9's from the same lot April 25) 1909; accession No. 41,082, 6 9's. (4) 2 d's) 2 9's) part of 7 d's, 3 9's reared October 2 from Musca puparia (see 11)) parents of the next two numbers ; accession Nos. 40,2d8, 1 8) 1 9) and 40,246, 1 dy 1 9. (5) 4 d's) 19 9's reared October 20 and November 7 from single Musca puparia in confine- ment) progeny of the single pair of accession No. 40,248 (see pre- ceding) ; accession Nos. 40,249, 3 d's) 10 9's and 40,269, 1 d) 9 9's (6) 1 d) 14 9's reared October 20 to November 7 from 15 Musca puparia in confinement) progeny of the single pair of accession No. 40,246 (see 4) ; accession Nos. 40,247, 1 3, 7 9's and 40,268, 7 9's. (7) 3 3's reared September 26 from three Musca domesiica puparia formed from maggots in horse manure and exposed to parasitism in the insectary September 8 to 11 ; accession No. 40,144, 3 d's. (8) 4 d's reared from four of the same host lot, September 27' ; accession No. 40,146, 4 d's. (9) 2 d's reared from two of the same host lot September 28; accession No. 40)150) 2 d's. (10) 2 d's, 7' 9's
reared from nine of the same host lot September 30; accession No. 40,153, 2 d's) 7 9's. (1 1) 2 parthenogenetic females) reared from two puparia of lot 4 in preceding, parents of the following; acces- sion Sos. 40,298 and 41,000, 2 9's. (12) 2 d's reared October 24 from two puparia of Phormia regina (Meigen) ) parthenogenetic



================================================================================

19101 Girault and Samiers - Chalcidoid Parasites 153 progeny of the preceding number; accession Nos. 40,299 and 41,- 001, 2 d's. (13) 5 d's, 9 9's reared as in lot 4; discarded. (14) 3 d's, 12 ?'s+42 reared October 4 with several fipalangia and 1 6' Pachycrepoideus dz~bius, from 57 Musca domestica puparia, exposed to infestation September 8-11 ; accession No. 40,171, 3 d's, 12 9's. (1 5) 22 9's-J-8 reared from 30 of the same lot as 14, the same spe- cies present in larger numbers, October ll ; accession, No. 40,205, 22 9's- (16) 1 9 collected in insectary around fly-breeding cages, September 10, parent of the next number; accession No. 39,965, 1 9. (17) 7 9's reared in confinement from 7 puparia of Musca domestica October 1, progeny of the single female of the preceding; accession No. 40,169, 5 9's. (1 8) d, 1 3, each removed October 13 from single puparia of Phormia regina (Meigen) obtained from garbage at the city dumping-grounds, C harn~aign~ September 23 ; accession No. 40,- 217, 1 d, 1 9. (19) 1 9 reared from a larva of Phormia regina, col- lected in garbage at the city dumping-grounds) Champaign, October 2 1, and removed from the capsule containing the host larva on No- vember 6; accession So. 40,258, 1 ?. (20) 2 d's, 2 9's reared from four Musca domestica puparia September 29, parents of the next number; accession No. 40,242, 2 d's, 2 9's. (21) 2 2's reared in con- finement from two puparia of Phormia regina (Meigen), October 19, progeny of the preceding; accession No, 40,243, 2 9's. (22) 3 d's, 3 9's reared from six Musca domestica puparia, Septembe~ 30) parents of the next; accession No. 40,244, 3 s's, 3 9's. (23) 1 6, 1 9 reared in confinement from two puparia of Phormia regina (Meigen), October 19) progeny of the preceding; accession No. 40,245, 1 d, 1 9.
The brief duration of the investigations and the lack of time and opportunity prevented an extensive study of the life-history and biology of this parasite, and because of its lesser abundance and the somewhat greater difficulty experienced in handling it in con- finement, not as much was learned concerning it as in the case of Nasonia brevicornis Ashm. It is more sensitive than the latter, has an apparently limited number of hosts and is solitary; yet, not- withstanding these, with time and opportunity, its biological history could be learned with ease in the laboratory, as the females are not



================================================================================

154 Psyche [August
at all adverse to ovipositing in confinement) as in the case of Spalan- gia and many other Chalcidoidea. But seemingly it is not as prolific and as general a parasite as is Nasonia. WTe have not obtained positive data concerning the entire seasonal history of this parasite) but our observations indicate that it confines itself principally to the puparium stage of the house fly) following this single host throughout and hibernating in the host puparium as a larva) pupating and emerging early in the spring in time to attack the first host generation. The investigations concerning the house fly) and during which this parasite was discovered, did not com- mence until late in July, and the parasite did not appear) so far as we know, until the first week in September. From then on) until freezing weather commenced) it was comparatively common. It was reared from host puparia collected on September 23; and again, nearly a month later) from hosts collected on October 21, from a garbage heap then literally swarming with muscid maggots (Musca, Chrysomyia, Phormia) ; and from this last lot of puparia a few adults of the parasite had emerged by November 6. On October 21 hibernation had probably commenced, for although adult Spalangia were found to be rather numerous in the soil around the muscid puparia at the garbage heap, neither raptor nor Nasonia brevicornis were seen. Further, hosts collected on November 14) 1908, from the same garbage heap) then covered with snow, when confined in the warm insectary, produced both adult raptor and Nasonia brevi- cornis which emerged about a month later, their development having evidently been hastened by the warmth. Facts such as these) strongly indicate hibernation in the host puparia and analogy would lead to the belief that this species has a winter history somewhat similar to that found in Nasonia brevicornis. As briefly as possible, we summarize the few special experiments conducted with this parasite in the laboratory. I. An adult female captured in the insectary around fly-breeding cages, September 13) was at once confined in a vial with a single puparium of Phormia regina; oviposition was observed within the next 24 hours, after which the parasite was released. No emer- gences followed. However) the host was examined in Marchy 1909, and found to contain fragments of the host pupa, the dead larva of this parasite, its body blackened but still soft up to May 20 follow-



================================================================================

19101 Girault and Sanders - Chalcidoid Parasites 155 ing and its peculiar meconium. Hence, this parasite attacks Phormia regina in confinement.
11. a. On October 1, a pair of adults just reared from Musca puparia in horse manure were confined with 40 healthy puparia of the same host reared in confinement from maggots in garbage. Ovi- position occurred and on October 20 following, four males and 19 females emerged as the offspring of the single female, making a total progeny of 23.
b. Another pair from the same source and emerging at the same time were similarly confined with 30 fresh Musca puparia reared from the maggots in garbage. Reproduction occurred and on Octo- ber 20, one male and 14 female parasites emerged as the total progeny of this pair.
Hence in confinement, single females were able to kill 23 and 15 hosts respectively, necessarily laying eggs to the extent of those amounts.
111. A single female parasite captured around the fly cages in the insectary, September 10, was confined in a glass vial with 11 healthy puparia of Musca domestica reared from maggots in horse manure; the parasite was confined with the hosts at 11.50 a. m. the day of capture. As a result, on October 1, seven adult females had emerged, the total progeny; two of the remaining hosts died but examination disclosed no symptoms of parasitism; the other two produced 1 d and 1 9 of the host on September 14. IV. Eleven females reared from 11 puparia of Musca domestica in horse manure September 29-30, and isolated at emergence - hence virgin - were separately confined during September 30 with single puparia of Phormia regina. Reproduction occurred and in three cases single males resulted as the progeny of three of the virgin parents; adult hosts emerged in three cases and the remain- ing hosts died without showing symptoms of parasitism. Hence parthenogenesis occurs with this parasite, the unfertilized ova pro- ducing males. Here, there can be no doubt but that the females were unfertilized, mating within the puparium, obviously, being impossible.
V. a. September 29, two males and two females of the parasite reared from four puparia of Musca domestica on the same day, earlier in the morning, were confined with 15 puparia of Phormia regina. Oviposition was observed at 11.45 a. m., and doubtless



================================================================================

106 Psyche [August
occurred again.
The resultant progeny proved to be two females from two of the puparia, emerging on the 19th of October. b. Experiment similar to a.
The following day three pairs of
the parasite from the same source as in preceding were confined with 17 of the same host puparia, the resulting progeny proving to be one male and one female, emerging on October 19 following. The experiments indicate fecundity, give the approximate dura- tion of the life cycle and establish parthenogenesis, which, however, remains to be verified. They also show the readiness with which the puparia of Phormia are attacked in confinement. As the observations on all points of the life history and biology of this parasite were necessarily desultory, they can be presented in no other way than one seemingly fragmentary. For convenience and brevity they are summarized or collected under the following headings.
A. Nature of Parasitism.
In the 309 (77 ^'s, 181 Q's, 51 unde-
termined sex) cases of parasitism which were isolated in small gela- tine capsules with special reference to the nature of parasitism, of which all but nine of the hosts (4 ^'s, 5 9's of the parasites) were Musca dornestica, every one yielded but a single parasite, which shows beyond doubt that the species is solitary in habit, even when - rarely - attacking comparatively large hosts such as Chrysomyia and Phormia are. In a critical examination of the hosts, after the emergence of the parasite, it was found that in nearly all cases they were considerably reduced in bulk, but not noticeably in length, recognizable as pupae, flattened, along the abdomen especially, hard- ened, shrunken and blackened - not collapsed or eaten away - indicating that the larval parasite was attached to the external body-wall of the host, obtaining its nourishment by absorption through it. This indication has been proven to be a fact by several direct observations made on dissected hosts, known to be parasitized by this species, and the further fact established, namely, that the larval parasite has no particular choice as regards the portion of the body of the host to which it attaches itself or rather to which it becomes attached. The destruction of the host is more complete than with Nasonia,
for some host pupae are mere hollowed-out



================================================================================

19101 Gimult and inlanders - Chalcidoid Parasites 157 shells of the venter, but less so than is the case with Spalangia. In a few instances the hosts were mere fragments, but the great majority were as has been described.
After emergence of the adult parasite, an examination of the host puparium reveals at first the shrunken and blackened remains of the host pupa lying in its natural position along the floor of the puparium and attached to it, usually along the dorsum of the caudal portions of the abdomen, the yellowish pupal cast of the parasite and then caudad of the host remains, lying upon the floor of the puparium, free, the peculiar, round-angled, dark meconium of the parasite larva; or the latter may be attached to the host remains as in Spalangia, there resembling a dark clot. As this meconium is characteristic, and can be readily distinguished from that of Spalan- gia, and hence forms an available means of identity when others are absent, by way of description it may be stated that, to the naked eye, it resembles a small solid, black-brown bead, about thrice the size of a visible grain of sand, resembling somewhat a coarse grain of powder, but not as irregular or as angular, measuring actually about .8 mm., its general outline convex and dome-shaped, the bottom flat, and the convex upper side, with a concavity, groove or impression along or in its center or at one end; this impression is quite often segmented, and as it is known that it is formed by the abdomen of the parasitic pupa which rests in it, the segmented appearance is due to the impression made in the then soft meconium by the in- cisions of the abdominal segments of the larva; the place of this groove is variable, and it may be absent, tending to show that the pupa of the parasite was not attached to it in the usual way; the edges of the impression are quite often acute or sharpened ridges; from above the meconium's outline is circular, with some irregular angulation; rarely it is quite irregular. It is much smaller in diameter - at least by a half -than the meconium of Spalangia which is wider and flatter, lozenge- or discus-shaped, and hence the two are readily distinguished on comparison. So far as the evidence goes, the manner or nature of the parasitism does not differ for sex of the parasite nor for species of the host. However, in four authentic instances, instead of the puparium stadium being affected, it was the larval stadium. The hosts in these instances were Chrys- omyia macellaria and Phormia regina and the parasites emerged from single, nearly full-grown larvae isolated in capsules.



================================================================================

158 Psyche LAugus t
B. Emergence of the Adult.
When perfect and mature, having
cast the pupal integument and rested, the adult parasite in order to obtain its freedom cuts a single rounded hole, measuring from 0.60 to 1.25 mm. diameter, through the puparium with its mandibles. This exit-hole varies in position but is usually cephalad or caudad and in the dorsal aspect. Its edges are ragged or serrated. It does not vary for sex or host and is not unusual. In rare cases the parasite may make as many as four exit-holes, obviously because of its failure to accomplish its exit readily, as is normal. So far we know of no characteristics distinguishing the exit-holes of this parasite from those of Spalangia or Pachycrepoideus. In regard to the time of emergence. The two sexes appear almost simultaneously, but our rearing records indicate an earlier appear- ance of the male as is usual. This sex, in a cycle lot of the same age, may appear from 24 to 36 hours earlier than the females, but not all together, the time given referring to the individuals of earliest appearance. The tendency in development is for a more rapid maturity of the males, taking the sex as a whole. C. Oviposition; Number of Eggs Deposited. The facts concern-
ing this habit are not well known and our observations are briefly stated. In one of the two cases observed, the host being Musca do- mestic~ Linnaeus, the position of the female was essentially the same as with Nasonia brevicornis Ashm.; the ovipositor was inserted into one end of the host dorsad and 90 seconds were occupied in inserting or boring the ovipositor into the host, and the ovipositor was fully inserted for 105 seconds. In the other case observed (September 9, 1908)) the female stood lengthwise along the dornestica puparium, along the median line dorsad, and inserted the ovipositor between two caudal segments; the antennae and abdomen were moved slightly during the operation which lasted for seven minutes (6.15 a. m.) ; subsequently during the same day, this same female was observed making (apparent) oviposition into the same host, so that, though solitary, several ovipositions into single hosts may occur (confine- ment). As already stated, occasionally (rarely) the female may deposit into maggots, apparently when young, but it is a question how this occurs or under what conditions it could be accomplished. Regarding the number of eggs deposited. But two observations of worth were made concerning this, as recorded on a previous page (experiment 11.1. Here two pairs of adults were given access to a



================================================================================

19101 Girault and Sanders - Chalcidoid Parasites 159 number of healthy hosts, allowing some range in choice as regards the number of progeny. In case a, 23 progeny out of a "possible" 40 resulted, and in case b, 15 progeny out of a "possible" 30 re- sulted. As these pairs were fresh and had not reproduced pre- viously, the results at least give us some notion concerning fecundity of the species.
D. Length of Life Cycle. We know nothing concerning the dura- tion of the different stages, and but little concerning the duration of the cycle as a whole. What has been learned, was obtained by experiments conducted in confinement and is summarized in the following table :
TABLE I.
DURATION OF THE LIFE CYCLE IN Muscidifurax raptor, SEVERAL CYCLES, 1908.
Lot
No.
"Number of
Progeny.
Eggs
Deposited.
Hours.
22
0
6
0
4
Average. . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . 1 19 1 17 Adults
Emerged.
-
-
E. Proportion of the Sexes.
Of the 288 reared specimens of this
species concerning which the nature of the sex was recorded, there were 85 males and 203 females, or nearly two and a half times more females than males. This high preponderance of the females is unexpected in view of the natural history of the species, but par- thenogenesis may account for it, following as it does no general taw in the Hymenoptera. The figures given are for the whole total of the specimens reared by us, either artificially or from hosts obtained in nature and the proportions may be warped. Of the former - those bred in confinement, hence artificially -totalling 52, but 1 Approximated to hours. ,
Duration of the
Cycle.
Days. 1
I I
20
20
19
19
19
Noon, Sept. 10
Noon, Sept. 29
Noon, Oct. 1
Noon, Oct. 1
10 a. m., l0ct. 1
Noon, 1Oct. 19
9a.m.,Sept.303p.m.,Oct.19
Noon, Oct. 20
4p. m., IOct. 20




================================================================================