HUNGERFORD: AQUATIC HEMIPTERA. ik7(S) 
The Egg. 
Size. Length, .598 mm.; diameter, .234 mm. 
Color. Very pale greenish. 
Shape. Elongate oval, but not regular. Viewed laterally the top 
line is nearly straight, while the lower line is curved. The anterior pole is 
flattened on the side bearing the micropyle, which is a slightly curved, 
cylindrical peg. The surface appears reticulated with irregular hexa- 
gons when seen under compound microscope. 
Most of our knowledge of these curious little back-swimmers comes 
from Heinrich Wefelscheid’s paper, “Uber die Biologie und Anatomie von 
Plea minutissima Leach,” 1912. 
This writer made an extended study of the above species. He says it 
winters as an adult. That the female is larger than the male and that 
mating begins in May and reaches its height in early June. He figures a 
mating pair, and states that they may remain in copula as long as two 
hours. Eggs were found in the laboratory in decaying stems of “Ra- 
nunculus aquatiles.” They were placed in the stem with the long axis 
parallel with that of stem, which agrees with our observation on Plea 
-striola. Egg stage lasted three or four weeks, and the five larval stages 
took one and a half months. He says only one generation possible, 
though Kulgatz says apparently two. As to the life of the adult he 
remarks: ‘Die Imago kann mindestens noch ein zweites Mal uber win- 
tern und sich fortpflanzen.” He found them preying upon Daphnians, 
and said they lived a week without food (most any predator will do this), 
and adds “Sie satzen dann meistens in den Blattescheln oder on den 
Stenglen und sangten offenbar die Pflanzen safte ein.” 
In regard to its power to fly, he states ‘““Dennoch scheint es mir nach 
dem verhdaltnismassig kraftigen Bau der Flugel nicht sweifelhaft zu 
sein, dass das Tier, ebenso wie seine nahe verwandte N. glauca, noch die 
_Fahigkeit des Fliegens besitzt.” He notes also that,in the British Mu- 
‘ seum there is an example from Batavia taken at electric light. 
_ They are capable of making sounds under water and he reports finding 
-“Reibleisten” on the sternum of the mesothorax “mit Hilfe deren das 
- geriiusch wohl erzeugt wird,’ and finds a tympanal organ in the meso- 
thorax, as in Corixa. The remainder of his paper is devoted to many 
interesting structural studies which he has made. His paper is a 
doctorate dissertation and shows how much there is to be done with our 
own species. 
Genus NOTONECTA L. 
ce BIOLOGY. 
At the close of his “Revision of Notonectidez, Part I,’’ Kirkaldy stated: 
“T had hoped to give an account in this paper of the metamorphoses of 
_N. glauca L. Unfortunately my attempts of rearing this species from the 
- ova during two seasons have been only partially successful. I have, how- 
ever, reared three larval instars from ova deposited in captivity, and 
am aware of two more, so that Notonecta has at least five larval instars. 
“In the ultimate and perhaps also the penultimate larval stage, the 
species can always be determined by the structure of the head; in the 
first three, however, the shape of the head and eyes does not resemble the 
Stk Yh 
ane 
