PARADICHLOROBENZENE ON YOUNG PEACH TREES. 15 
Taste 9.— Mortality of peach-borer larve exposed to paradichlorobenzene in cages at 
insectary, Fort Valley, Ga., 1921. 
[All larvee exposed to the gas October 19, 1921. Sandy loam used in all cages.] 
| 
| | | Condition of larve. 
| oa 
} Oct. 26. Nov. 3. Nov. 10. 
Num-| Depth) Condition of R les 
Dose. | berof| in sail emarks. 
larve. soil. : a id = 
| | a|¢ a|g¢ e|g 
dialelslateisl ate 
| g15/S/s/F/E18 i512 
| Ala 4i/Alalia~al|Alal< 
i | | 
NCES Inches. | 
ae 5 3 | Normal Sid 8 8 oa Cee ee ee _...|....| Odor and crystal at close. 
5 Yo ot £4) OpeOr) ich 0:1; 1170 | 0 | Few crystals Nov. 10. 
H 5 My a do Se Pete ree LO [ac [eoec | eae Many erystals left Nov. 
3 5 3 See OY ee Shi Ol aio. LB BRD ORS ee Crystals left at close of 
cage. 
1 5 ag C See Ce 2g ae Se yh ie es a ah (eR SR 1 larva fed before death. 
1 5 dF ee O02 2 as Se pe Se a a a Ee ee | 2 larvee fed before death. 
1 5 i? Rae do-. 2: #2 a) Sh -2? 8 1G, 15... | Joc. t.2s 2 larvee fed before death; 
many crystals left at. 
close. 
14 5 3 j...-- des 022 AG ub eos SSA RR RS Be some 5 dead at 1 week’s expos- 
ure; over 1 ounce para- 
| dichl orobenzene left 
17 "| Oct. 26. 
1} 5 ® hea. do. Bee Ue Ee Ait olla} «fo eel oe aclaes 4 dead at 1 week’s expos- 
| ure; over 14 ounces para- 
dichlorobenzene left 
| Oct. 26. 
14 5 . 8 ee Be at Nihee CPacr) =e’ Seed Pees ager erode 3 dead at 1 week’s expos- 
ure; over 14 ounces para= 
| dichlorobenzene _ left 
Oct. 26. 
2 5 | es ee Ey tie ') ee RE ee ARE Fon 4 dead at 1 week’s expos- 
ure; over 14 ounces para- 
dichlorobenzene left. 
Oct. 26. 
1 5 6 | 180cubiccen-; 5] 0] O pee pees eee eee bees cee Larve fed before death. 
timeters of 
water add- 
ed. 
1 5 6 | 360cubiccen-} 1} 4] 0} 2; 2) 0} 1] 1 | 0 | Larve fed before death; 
timeters of no odor at bottom of 
|} Water add- cage Oct. 26; last larva 
ed. died Nov. 17. 
1 5 6 MO0cubiccen-| 1] 0; 4] 3} 1] 0} 1] O]| O| Larve fed before death; 
timeters of no odor at bottom of 
cone add- cage Oct. 26. 
Check. 5 3 | Normal...... 0; O| 5| O}11] 4| O} O|} 5] 1 larva away from food 
Nov. 3. 
: i i | 
1 Sluggish. 
Note.—All larv@ confined in flowerpots or battery jars 10inches high and 6inches wide, except several 
that were in cages 12 inches tall. Odor stronger than around treated trees in the field. . 
EFFECT OF TEMPERATURE AND ss et oe THE EFFECTIVENESS OF PARADICHLORO- 
NZENE. 
In determining the killing effect of paradichlorobenzene on peach- 
borer larve, with different degrees of temperature and different 
amounts of moisture, the standard 1-ounce dose was used through- 
out the experiment. In November and December, 1921, at a maxi- 
mum temperature of 69° F. and with the moisture in the soil ranging 
from 9.15 per cent (normal soil) to 20.15 per cent, all larvee were 
killed in 13 days. At 64° F. maximum, and 1.24 per cent moisture 
(normal soil), 5 larve were killed in 7 days. At 64° F. maximum, 
with from 8.34 per cent to 11.44 per cent moisture, all larvee were 
killed in 15 days. In the cage with no paradichlorobenzene, 4 larvee 
remained alive and fed continuously throughout the experiment, 
and one died, probably from lack of food. Table 10 gives a sum- 
mary of the results obtained. 
