The females of many species of cockroaches insure varying degrees of protection to the developing young in their ways of disposing of the oötheca after it has been formed. The extent of this association between the mother and her developing progeny varies from the minimum amount of time spent by oviparous females in concealing their oöthecae, to the duration of embryogenesis in the so-called viviparous species, a period of over a month or more.
Haber (1920a) observed a female of Periplaneta americana chew a groove in a piece of pasteboard into which she attempted to deposit her oötheca. The oötheca failed to adhere to the shallow hole and fell to the floor. After several futile attempts to replace the oötheca in the hole, the female finally left the egg case on the floor of the cage and coated it with an oral secretion to which she attached bits of trash. During this operation she chased other females away when they ventured near the site. Qadri (1938) described the behavior of the female of Blatta orientalis in concealing her oötheca in a hole that she dug in sand; she deposited the egg case in the hole, coated it with saliva and sand, and then refilled the pit. Rau (1943) described in detail how females of P. americana and B. orientalis covered their oöthecae with wood dust or sand in holes they had prepared in the substrate. Both species placed a sticky oral secretion in the holes and then deposited their oöthecae therein. After coating the oöthecae with more sticky secretion, the females adjusted the oöthecae so that the keels were uppermost and then carefully concealed the oöthecae with the excavated debris. Both females spent over an hour in the act. Rau (1924) previously reported that of 90 oöthecae deposited by B. orientalis in jars containing earth and trash, 36 were placed in crevices or excavated holes, and 38 were hidden by being covered with dirt stuck to them with saliva; only 16 were left uncovered.
Edmunds (1957) described oviposition by Periplaneta brunnea. Some females spent from 30 to 40 minutes secreting from the mouth a frothy substance that was smeared on the substrate; the egg capsule was deposited in the secretion and covered with additional froth, which hardened into a very strong cement. Some females spent as long as two hours coating the capsule after it was deposited. It was not stated whether the oötheca was otherwise concealed. The female remained with her body over the oötheca for several hours and drove away other cockroaches which approached.
Sonan (1924) observed that Periplaneta americana and Periplaneta australasiae spent from 40 minutes to an hour covering their oöthecae, and that if the females were frightened away from this activity, they returned again to complete it. As well as excavating holes in the substrate in which to deposit its oöthecae, P. americana also avails itself of readymade crevices of appropriate size (Ehrlich, 1943). Species of Epilampra in Malaya were said by Annandale (1900) to deposit their oöthecae in crevices in floating logs just above the water line. However, Shelford (1906) stated that four genera (including Epilampra) of the subfamily Epilamprinae are "viviparous," in which event the females would carry their oöthecae within their bodies during embryogenesis and would not place the oöthecae in crevices in logs.
The female of Cryptocercus punctulatus was observed to make a groove in a piece of wood, then carry her oötheca 6 inches from where she had dropped it and place it in the groove; she covered the oötheca so that only a portion was visible (Cleveland in Cleveland et al., 1934). Dr. W. L. Nutting (personal communication, 1954) collected a number of oöthecae of C. punctulatus in the field and found each one almost completely sealed off with bits of wood in a deep groove in the roof of a chamber in a log. The keel of the oötheca was visible but the rest was well camouflaged. He stated that "The adult pair usually frequents the chamber at this time, while their broods of previous years occupy neighboring galleries."
Berland (1924) observed a female of Loboptera decipiens filling a hole (the abandoned nest of a hymenopteron) with earth that she carried in her mouth; he later found her oötheca behind the earthen barricade which she had erected.
In summary, the following species of oviparous cockroaches have been observed concealing their oöthecae (only those references not previously cited are given): Blatta orientalis; Cryptocercus punctulatus; Ectobius sylvester (Harz, 1956, 1957); Epilampra sp.; Eurycotis floridana (Roth and Willis, 1954a); Loboptera decipiens; Balta scripta, Methana curvigera, Methana marginalis, and Methana caneae (Pope, 1953a); Pelmatosilpha marginalis, Pelmatosilpha purpurascens, and Nauclidas nigra (Bunting, 1956); Periplaneta americana (Haber, 1919; Adair, 1923; Seín, 1923; Nigam, 1933; Gould and Deay, 1938; Rau, 1940a); Periplaneta australasiae (Girault, 1915b; Spencer, 1943; Pope, 1953); Periplaneta brunnea (Roth and Willis, unpublished data, 1958); Periplaneta fuliginosa (Gould and Deay, 1940); Periplaneta ignota (Pope, 1953); Supella supellectilium (Flock, 1941). Undoubtedly other oviparous species that drop their oöthecae long before the eggs hatch also make some attempt to conceal the oöthecae by placing them in crevices or covering them with debris.
Sometimes the oöthecae are deposited but not concealed. Hafez and Afifi (1956) reported that in Egypt Supella supellectilium attaches its oötheca to a suitable substrate with a gummy oral secretion but leaves the egg capsule otherwise exposed. We (1954) have noticed similar behavior in laboratory colonies of this species and of Blatta orientalis, as have Gould and Deay (1940). Cornelius (1853) stated that the female of B. orientalis takes care of the safety of her offspring to the extent of usually dropping her oöthecae in places which are dry and raised above the ground, although rarely one also may find some oöthecae scattered on the ground. For lack of suitable material females of Periplaneta americana sometimes did not conceal their oöthecae (Nigam, 1933). Frequently in laboratory colonies P. americana merely drops the oöthecae loosely in sand or food "in contrast to P. australasiae, which almost always went to considerable trouble to fasten their eggs securely and to conceal them with debris" (Pope, 1953). If conditions under which Nauclidas nigra is kept are not suitable, the female will drop her oötheca anywhere (Bunting, 1956). Rau (1940) stated that the female of Parcoblatta pensylvanica does not conceal her oötheca. However, Gould and Deay (1940) stated that this species deposits its oöthecae loosely behind bark. Ellipsidion affine and Ellipsidion australe attach their oöthecae to bark or the underside of leaves but apparently make no attempt to conceal them (Pope, 1953a).
The females of most of the above species have no further familial association with their offspring. The eggs hatch with no attention from the mother who is probably not even in the vicinity at that time. The young apparently do not react to the presence of the parent, as such, after hatching. This is not unexpected, as several additional oöthecae may have been deposited by these oviparous females before the eggs of the first oöthecae hatch. However, a different behavior is encountered among species that do not form a second oötheca until after the eggs of the first have hatched (see below) and in the so-called colonial species.
Shaw (1925) reported that in Australia both Panesthia australis and Panesthia laevicollis appear to live in families, and that one usually finds a pair of adults associated with from 12 to 20 nymphs in different stages of development; he continued, "it is only where the molts are very abundant that one loses sight of this familial habit." Tillyard (1926) also stated that the Australian species of Panesthia live in burrows in soil in strict family communities of a pair of adults and 10 to 20 nymphs. A related colonial species, Cryptocercus punctulatus, lives in both sound and rotten logs in colonies consisting of a pair of adults and 15 or 20 nymphs, probably representing two or three broods (Cleveland et al., 1934; Cleveland, 1948). Chopard (1938) has cited this association as an example of gregariousness, which it may well be; however, the presence of only one pair of adults in each colony suggests a more intimate relationship.