THE PEAR LEAF-WORM. 13 
Table V, 122 eggs were marked on the trees. Thirty eggs died 
before hatching or were infertile. The remaining 92 hatched and 
16 larve disappeared and 3 died before molting. Thus 73 larvee 
cast their first skin under observation. Of these, 6 disappeared and 
2 died before casting the second skin. Thus 65 larve molted a second 
skin under observation. Of these, 5 disappeared and 5 died (1 being 
destroyed by a coccinellid larva) before shedding the third skin. Of 
the 55 larve which cast the third skin, 8 subsequently disappeared 
before they were ready to drop to the ground. The larve under 
observation were taken into the laboratory insectary after their 
third molt, but were not inclosed in cages, so that those which desired 
to move away could do so. On the trees most of the larvee which 
disappeared were dislodged during the operation of molting. 
TasLE VI.—Summary of Table V. 
Tnstar. Maximum.| Minimum.| Average. 
Days. Days. | Days. 
EPI SNM SE RUAN CIN Sand Se EVAR aol Le 8 3 5.3 
POLE AUGER SLE el ye UA IRL OT ASN aR A EMS 7 2 3.4 
Oy REI Leda cE mento yet k Ss PLU aa eth 7 2 4.2 
Ce APCS RE RM Hoey a ste) es fet AL DO ee Sea 10 4 6.6 
Total larval period on trees....-...-. 23 16 18.4 
The data in Tables V and VI are in striking contrast to those 
recorded from San Jose (Table IV), in which the average period spent 
by the larvee in vials was 31.6 days. It would appear that the San 
Jose individuals were retarded by reason of the abnormal character 
of their food as a result of the feeding of cut leaves. It might be 
added that the temperature during the period of larval growth in 
1913 at Walnut Creek was higher than the mean average for that time 
of year, and toward the end of April great daily fluctuations occurred; 
for instance, on April 24 and on May 38 there was a range of 48° F. 
Tables VII and VIII give the larval life history at Wenatchee, 
Wash., in 1915. 
