W. L. Nutting.
Observations on the Reproduction of the Giant Cockroach, Blaberus craniifera Burm.
Psyche 60(1):6-14, 1953.

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OBSERVATIONS ON THE REPRODUCTION OF
THE GIANT COCKROACH,
BLABERUS CRANIIFERA BURM.
BY W. L. NUTTING
Biological Laboratories, Harvard University In his Embryology of the Viviparous Insects, H. R. Hagan (1951) cites nine species of roaches recorded as exhibiting some type of viviparity, or oviparity approaching vivi- parity. Chopard (1950) and Van Wyk (1952) have furn- ished two additional examples of viviparous blattids. Much of the evidence for viviparity has been indirect; that is, it has been based on dissections of gravid females, while in scarcely half the cases has the birth process actually been witnessed. Among the species mentioned by Hagan are the West Indian Blabera fusca Brunner (Saupe, 1929), and a Bolivian Blabera species (Holmgren, 1903). (Blabera fusca Brunner can probably be referred to craniifera Burm. according to Rehn and Hebard (1927).) Over the past seven years I have had the opportunity to observe rather closely a flourishing culture of Blaberus craniifera Burm., originally started from Florida specimens by Prof. C. T. Brues. (This roach is limited to Cuba in the West Indies and ranges from southern Mexico to British Honduras on the mainland; it has undoubtedly been introduced to Key West from Cuba.) During this period I have found newly hatched nymphs dozens of times, but only recently have I observed parturition itself. Before recounting this event, it seems appropriate to include available information on mating, the little-known spermatophore, and other relevant details on the reproductive habits of this large laboratory roach.
Blaberus is rarely active during the daytime, even in the laboratory, and I have never seen courting behavior. How- ever, Saupe (1929) described the one case of love play and copulation for B. fusca which he observed during daylight. The actions were generally much like those detailed for



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19531 Nutting - Reproduction in Blaberus 7 some of the more common roaches (see Roth, 1952), except that no dorsal glands are known which attract and engage the female as in Blattella. The male vibrates his antennae and goes through brisk quivering motions, sometimes raised up on his legs. After contact stimuli from the interested female he raises his wing's, while the female advances over his abdomen as far as his raised wings to the "female supe- rior pose".
As the male makes contact with the female's genitalia, they simultaneously turn in opposite directions to complete copulation in the "false-linear position" which is typical for the roaches. The pair 'observed by Saupe re- mained together for 80 minutes, but I have noted many pairs together for four hours and more which is much longer than is usual for most roaches.
Many texts lilst the 'occurrence of spermatophores in cer- tain membem of the Thysanura, Odonata, Neuroptera, Lep- idoptera, Coleoptera, and several subgroups of the Orthop- tera. Until recently, oddly enough, it was not generally known that this method 'of sperm transfer is also used by at least some of the blattids. Zabinski (1933) first described and figured the spermatophore for Blatta orientalis, while Qadri (1938) reported some conflicting observations on spermatophore formation for the same species. Hagan (1941) mentioned the genital pouch as a receptacle for the spermatophore in Diploptera, but did not describe it. The spermatophore of Pe&planeta mericana was de- scribed and figured in position by Gupta (1947). The formation of the spermatophore of Blattella germanica is described and discussed by Khalifa (1950). Roth (1952) presented notes on the spermatophores of Blattella, Blatta, and Periplaneta. Recently Van Wyk (1952) described the spermatophore of Leucophaea mderae. The present obser- vations on Blaberus now make a total of five subgroups of the Blattaria which are known to form spermatophores. This strengthens Khalifa's presumption that spermato- phores are of general occurrence among the rloaches. Figs. 1 and 2 show the position of the spermatophore (Sph) in Blaberus shortly after copulation. 'The freshly deposited spermatophore is a tailed, pearly-white spheroid, about 3.5 mm. in diameter. A clear, jelly-like mass fills



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8 Psyche
[March
the vestibule (Ve) and cements ('stippled area) the sperm- atophore into the genital pouch. According to Qadri the spermatophore of Blatta contains a number of sperm cap- sules, while Khalifa and Van Wyk described two sperm sacs in those of Blattella and Leucophaea. In Blaberus the spermatophore is irregularly divided into a small and a large compartment, while two sperm ducts lead from the larger one to oppose the
spermathecal orifices. Whereas
most of the roaches previously noted have not retained their spermatophores longer than 24 hmours before dropping them, one Blaberus female was noted to retain her sperma- tophore intact flor five days, when on the sixth day a mass of chalky fragments and greyish jelly was observed in her genital pouch.
As in the other roaches which retain their eggs for a considerable time, the ootheca resembles a thin, transparent plastic bag drawn tightly about the eggs. It is quite smooth and, as it varies in thickness, a dull ochreaceous to a bright chestnut in color. A point which has previously been over- looked in Blaberus is that the ootheca is not complete, so that the ~micropylar end of each egg is plainly visible through a slit usually wider than one egg. The extremely delicate lootheca of Diploptera as described by Hagan, never covers more than half of each oticyte, and may not even cover the older eggs. Although Blaberus does not approach this extreme, the pro- and mesothorax of each embryo are virtually free of the ootheca shortly before birth. This open type of ootheca may be of some importance to embryonic respiration within the brood pouch as suggested by Hagan. The elaborate arrangement of air tubes through the keel of the conventional armored roach otitheca (Lawson, 1951) EXPLANATION OF PLATE 1
Fig. 1. Blaberus craniifera Burm. ventral dissection of female repro- ductive system showing spermatophore (Sph) cemented (stippled area) into the genital pouch over the gonopore. The posterior ventral wall of the genital chamber has been removed. Fig. 2. Sagittal section through region shown in Fig. 1. AG, accessory gland; An, anus; BrS,
brood sac; C, colon; Od, oviduct; Ov, &ary ; Ovp, ovipositor; R, rectum; S, sternite; 'Sph, sperrnatophore; T, tergite; Ve, vestibule; Vul, vulva.



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NUTTING - BLABERUS CRANIIFERA




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10 Psyche [March
would certainly be unnecessary, if not actually impractical here.
One of the largest oothecae I have seen contained 45 eggs and measured 8 x 35 mm., while an unusually small one containing 23, probably from an old female, measured 4 x 16 mm. The average number of eggs found in 14 oothecae was 36.4. Saupe (1929) gave an average of 23.25 eggs for 8 oothecae, ranging from 11 to 38 per ootheca in B. fusca. Stewart (1925) reported an ootheca yi x inches con- taining 44 eggs from a specimen of B. cubensis Saussure. (Rehn and Hebard (1927) refer this species to B. discoidal- is Serville.) Two oothecae of the Central American B. tmpezoideus Burm. measured 7 x 35 and 4.5 x 31 mm., and contained 40 and 41 eggs respectively. Diplopteru, which has been more thoroughly studied than any of the viviparous roaches, exhibits a pseudoplacental type of vivi- parity and forms an ootheca normally containing but 12 eggs. All other known viviparous roaches produce many more eggs at a time, the numbers per ootheca generally falling within the limits reported for these three species of Blaberus.
While in the brood sac, all the eggs in an ootheca have the micropylar ends directed toward the left. The smallest eggs found in newly formed oothecae measured 1.7 - 2.0 x 4.5 - 5.0 mm. ; the largest, shortly before hatching, 2.5 x 8.2 mm. In the young germ band stage the pleuropodia re- semble short, thick-stalked, immature mushrooms, and pro- ject back to the posterior margin of the second abdominal segment. In the chitinized embryo, shortly before they are resorbed, they appear as long, thin-stalked mushrooms ex- tending to the middle of the third abdominal segment. They consist of a base and bulb only; there is no evidence of any pleuropodial extension as found in Diploptera. The eggs contain a large amount of yolk, and a considerable amount is present shortly before hatching. In the absence of any embryological studies on Blaberzis, little more can be said concerning embryonic nutrition; it does not seem likely that the mother provides any more than the original yolk.
Many times I have seen females with a newly formed



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19531 Nutting - Reproduction in Blab erw 11 ootheca protruding about two-thirds of its length from the brood sac. Some of these females were segregated, and their oothecae were usually completely returned into the brood sac within a short time. This act apparently signals the completion of an ootheca and the beginning of the incubation period, as has been observed in Gromphadorhina by Chopard (1950). Neither the duration of gestation nor the span of female reproductive life is known for any of the species of Blaberus, although the former may last for more than two months. Females sometimes discard an ootheca ; this has occurred most notably after the roaches have been disturbed and handled during cage-cleaning. Except in two cases noted below, none of these otithecae has been known to hatch.
Recently a relatively inactive female was found with about half the length of her ootheca extruded from the brood sac. At least the pro- and mesothorax of each visible embryo were free of the ootheca. The ensuing events of hatching were observed under a low-power dissecting micro- scope. All of these embryos were rapidly swallowing air, and the bubbles could easily be seen passing through the head capsule into the enlarging crop. Within 2 or 3 min- utes the embryonic cuticle on one individual had split; after 60 to 90 seconds, with some side to side struggling, it was free. Alth'ough the abdominal movements of the female indicated that she was trying to expel the ootheca, she was unable to extrude more than three-fourths of its length. I therefore removed the egg ease, and within 10 minutes all but four unfertile eggs had hatched. On becoming free the embryos gradually stopped swal- lowing air; at this point they were cylindrical and about 10 mm. long. They began telescoping their abdominal seg- ments and within a few seconds they had assumed a flat- tened roach-like appearance measuring about 7 mm. long. The air is probably expelled through the mouth. The young roaches do not leave the mother but swarm over the ootheca practically consuming it in a short time. Saupe (1929) suspected the mother of devouring the o6thecal remains. A degree of maternal solicitude is exhibited by this roach, for many times I have observed the female to remain



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12 Psyche
motionless for an hour or more with her unpipented brood clustered around and beneath her body. The nymphs are completely pigmented in about 6 hours. I have recorded the next molt as occurring within 15 to 36 days for four different broods.
Although deposited oothecae generally do not hatch, a mature one, picked up two days after the cage had been cleaned, did hatch after considerable handling. While ex- amining another ootheca six days after its deposition, it wag noted that the embryos were swallowing air. Slight pressure on the otitheca while held between the fingers finally resulted in the successful hatching of 14 normal nymphs. Two more nymphs were obtained from this same ootheca upon considerable manipulation ten days after its deposition. On numerous other occasions mature Gthecae have been kept in humid petri dishes for two or three weeks without 'hatching. The hearts of these embryos continued beating until they finally died from mold or desiccation. These observations strongly suggest that the pressure exerted by the female on the dtheca during ex- trusion supplies the necessary hatching stimulus. Unless some such stimulus is applied to initiate the air-swallowing, mature embryos remain helplessly encased until death. The fine line separating owviviparity from viviparity seems to be whether or not the embryos hatch before deposi- tion. By strict definition, this single reported observation on the birth of Blabems nymphs would qualify it as an ovovi- viparous insect. Many more observations would be required to determine whether the female generally retains the oiitheca while the majority of the embryos hatch; it ap- pears to me quite impossible for the event to take place within "be confines of the brood sac itself. Although this categorizing is relatively unimportant, the features which place this fine laboratory insect between the more common oviparous roaches and the viviparous Diploytera are worth noting.
The ovarides have not been reduced in number (16 to 23 per ovary as opposed to 6 in Diploptera), and the ac- cessory glands are not aa highly modified as in Diploptera. Even though each ootheca contains a large nmnber of egg's,



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19531 Nutting - Reproduction in Blaberus 13 the period between Gthecae may be measured in weeks rather than in days as in Periylaneta (Gould and Deay, 1940). The brood sac is very large, and the development of the genital pouch approaches that of Diploptera. Lastly, the ootheca is soft, thin, and open, and is retained in the brood sac until hatching. In summary, the major modifi- cations toward viviparity in Blaberus have occurred in the mother and not in the embryo.
BIBLIOGRAPHY
CHOPARD, L.
1950. Sur l'anatornie et la dkveloppement d'une bla~tte vivipare. Proc. 8th Int. Gong. Emt. Stockholm, 218-222.
GOULD, G. E. and H. 0. DEAY
1940. The biol~ogy of six species of cockroaches which inhabit build- ings.
Purdue Univ. Agric. Exp. &a. Bull. 451, 31 pp. GUPTA, P. D.
1947. On copulation and insemination in the cockroach Periplaneta americana (Linn.). Proc. Nat. Insit. 'Sci. India, 13:65-71. HAGAN, H. R.
1941. The general morphology of the female reproductive system of a viviparous roach, Diploptera dytiscoides (Sew.) . Psyche, 48 : 1-9.
1951. Embryology of the viviparous insects. New York, Ronald Press. 472 + xiv pp.
HOLMGREN, N.
1903. Uetoer vivipare Insecten. Zool. Jahrb. Abt. Syst., 19: 431-468. KHALIFA, A.
1950. Spermatophore production in Blattella germanica L. (Orthop- tera :Blattidae) .
Proc. Roy. Enit. ,Sot. London, 25A: 53-61, LAWSON, F. A.
1951. Structural features of the oothecae of certain species of cock- roaches (Blabtidae). Ann. Ent. Soc. Arner., 44:269-285. QADRI, M. A. H.
1938. The life-history and growth of it:he cockroach Blatta orientalis Linn. Bull. Ent. Res., 29:263-276.
REHN, J. A. G. and M. HEBARD
1927. The Orthoptera of the West Indies: Blatti~~ae. Bull. Amer. Nat. Hist., 54:pp.257-262.
ROTH, L. M. and E. R. WILLIS
1952. A study of cockroach behavior. Amer. Mid. Nat., 47:66-129.



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SAUPE, R.
1929. Zur Kenntnis der Lebensweise der Riesenschabe Blabera fusca Brunner und der Gewachshausschabe Pycnoscelus surinamensis L. Zeiitschr. f. angew. Ent., 14:461-500. STEWART, A. M.
1925. Blabera cubensis (Orthoptera) and its ootheca. Entomologist, 58 : 57-58.
VAN WYK, L. E.
1952. The morphology and histology of the genital organs of Leuco- phaea maderae (Fabr.) (Blattidae, Orthoptera) . J. Ent. Soc. S. Africa, 15: 1-62.
ZABINSKI, J.
1933. Fonatiionnement des diff6rentes parties des appareils copula- teurs chitines males et femeUes de la Blatte (Periplaneta orientalis L.). C. R. Soc. Biol., 112:598-602. NEMESTRINIDAE (DIPTERA) OF IOWA AND MISSOURI. - A small collection recently sent by Mr. Jean L. Laffoon, at Iowa State College, contains a male of Neorhynchocephalus sackenii (Williston) collected at Sioux City, Woodbury Co., Iowa, June 10, 1949, by J. A. Slater and J. L. Laffoon. It was taken immediately above the mouth of the Sioux River, on top of the loess hills which border the Missouri River in western Iowa. Mr. Laffoon points out to me that this area contains some pllants and animals ordinarily found only farther west. It is the first record for any of the
Nemestrinidae in Iowa. Specimens of N. sackenii were also collected at Washington University Farm, 7 miles southwest of Clarksville, Pike Co., Missouri, by Mr. Robert A. Dietz, of the University of Tennessee. N. sackenii is now recorded from British Columbia and the states of Washington, Oregon, Montana, California, Idaho, Wyom- ing, Utah, Arizona, Colorado, New Mexico, Kansas, Okla- homa, Arkansas, Missouri, Iowa, Mi'cthiigan, and Illinois. I have seen specimens from Huachuca Canyon, Cochise Co., Arizona, August 17, 1950 (R. L. Langston). It is remark- able that there are as yet no records from Mexico. - J. BEQUAERT, Museum of Comparative Zoology, Cambridge.



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