12 
Psyche 
[March 
motionless for an hour or more with her unpigmented 
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 
was noted that the embryos were swallowing air. Slight 
pressure on the ootheca 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 
oothecae 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 ootheca 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 ovoviviparity 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 Blaherus nymphs would qualify it as an ovovi- 
viparous insect. Many more observations would be required 
to determine whether the female generally retains the 
ootheca while the majority of the embryos hatch; it ap- 
pears to me quite impossible for the event to take place 
within the 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 Diploptera are worth 
noting. 
The ovarioles have not been reduced in number (16 to 
23 per ovary as opposed to 6 in Diploptera) y and the ac- 
cessory glands are not as highly modified as in Diploptera. 
Even though each ootheca contains a large number of eggs. 
