- 4. BULLETIN 1824, U. S. DEPARTMENT OF AGRICULTURE 
C., the optimum for larval development, the female jays from 9 to- 
15 eggs. When intermittent temperatures of 1° and 37° are imposed 
for 24-hour periods throughout the life of the moth, it lives longer 
and lays 25 to 35 eggs. At temperatures intermediate between 20° 
and 37° not over 12. eggs are laid. The vital repose obtained by the 
lower temperature prolongs the life of the moth and_-an increase in 
egg production results. Temperature affects both the rapidity of 
egg-laying and the number of eggs deposited by Phthorimaea oper- 
culella (29). Glenn (28) states that low temperature delays egg- 
laying of the codling moth (Carpocapsa pomonelic). Isely and 
Ackerman (42), who have recently studied the oviposition of this 
insect, could detect no serious check in egg-laying under optimum 
light conditions till a temperature of 18.3°C. was reached. Below 
this few eggs were laid and oviposition ceased entirely at 16.7°C. 
The period of highest night temperature occurs immediately after 
sunset, which probably accounts for the heavy oviposition at. this 
time (Siegler and Plank, 74). Sharma and Sen (72) found that 
certain Indian mosquitoes preferred temperatures near 35° C. 
for oviposition, and high or moderately high temperatures under 
proper moisture conditions stimulate egg- laying in the house fly 
(Musca domestica) (Bishopp, Dove and ‘Parman, 8). It has been 
Hien by Roubaud (67) that Glossina palpalis Desv., which de- 
posits living larve. is active in this respect between approximately 
93° and 28° C., whereas at 30° C. reproduction is completely arrested. 
Lysiphlebus tritici Ash. (=A phidius testaceipes Cress.), a hymen- 
opterous parasite of the green bug (7 oxoptera graminum Rond.) 
attempted to oviposit, but Without success, at 1.7 ° C., the lowest tem- 
perature at which the oviposition activity of this species was ob- 
served (27). Temperature plays an important role in the Ee 
of H ovubeieon brevicornis (Wesmael) (34).° 
HUMIDITY 
Humidity is an important factor nm the egg-laying activities of 
many if not most insects. Shelford (72?) observed that tiger-beetles 
require moist soil for oviposition. By increasing the atmospheric 
moisture irom 55 per cent to 96 per cent, egg- laying of Toméicus 
typographicus was delayed from 1 to 7 days ( Hennings, 3D). 
Heavy precipitation delays oviposition in Carpocapsa pomonella, but 
whether from the effect of the moisture or from mechanical effects 
was not stated (Glenn, 28). High atmospheric moisture favors 
oviposition in the blow-flies (C alliphora spp., Lucilia spp., 81), 
and invariably imcreases the amount of egg laying in Drosophila 
melanogaster (1). It is also necessary for normal oviposition of the 
house fiy (8, 63. 64,68). According to Roubaud (67), the deposition 
of larvae by G lossina palpalis ceases when the atmospheric humidity 
reaches the saturation point unless the fly has previously been sub- ~ 
jected for several days to an accelerating temperature (28°C). The 
humidity of the usual habitat of this species is normally 90 per cent. 
Certain species of mosquitoes and other insects which lay their eggs 
upon the surface of the water probably develop a strong hydro- 
>The correct name for the species used by Hase (cf. Die Naturwissenschaft, Jahre. 
11, Heft. 39, p. S01, 1923) is juglandis. 
f 
