48 BULLETIN" 1147. IT. S. DEPARTMENT OF AGRICULTURE. 
Table 22. — Arsenic consumed by insects in feeding tests, 1919 — Continued. 
Species of insects 
Arsenicals and controls. 
Condition of 
larvae before 
being analyzed. 
Num- 
ber of 
larva? 
ana- 
lyzed. 
Arsenic 
per 
larva. 
Arsenic (parts 
per million) 
in— 
Tox- 
icity 
after d 
ducting 
and sample No. 
Larva?. 
Feces. 
mor- 
tality 
of 
control 
Potato-beetle 
larvae: 
39 
Commercial acid lead ar- 
senate. 
Commercial basic lead 
arsenate. 
Laboratory acid lead 
arsenate. 
Commercial calcium ar- 
senate. 
Laboratory calcium ar- 
senate. 
Sample 69 plus 1 gram 
lime per 418 cc. 
Laboratory barium arse- 
nate. 
Commercial magnesium 
arsenate. 
Laboratory sodium arse- 
nate plus Bordeaux 
mixture. 
Commercial zinc arse- 
nate. 
do 
do 
150 
125 
100 
150 
110 
80 
110 
130 
100 
100 
120 
130 
Milli- 
grams. 
0.0017 
.0020 
.0038 
.0026 
.0045 
.0042 
.0049 
.0029 
.0028 
.0018 
.0024 
.0051 
141 
168 
327 
205 
311 
330 
350 
223 
257 
172 
206 
460 
62.1 
28 
53.4 
68 
do 
57.9 
5 
do 
do 
62.7 
69 
61.8 
69B 
do 
61.9 
71 
do 
50.9 
62 
do 
57.1 
55 
do 
do 
do 
51.8 
23 
54.7 
64 
59.5 
74 
Laboratory copper ba- 
rium arsenate. 
do 
54.7 
The following facts are evident from Table 22 : About 40 per cent 
of the arsenic (samples 39 and 5) found in the samples of web worms 
was probably carried on the integuments of the larvae. As a general 
rule, the higher the average toxicity, the smaller is the quantity of 
arsenic found in the larvae. The ratio of arsenic found in the 
webworms to that found in their feces is about 3 to 5 for those 
arsenicals giving high toxicities, while for those arsenicals giving low 
toxicities the ratio is about 1 to 1. 
PHYSIOLOGICAL EFFECTS OF ARSENIG ON INSECTS. 
Symptoms of arsenic poisoning in the various insects used in the 
preceding experiments can not be fully described, because these 
insects were usually too sluggish to permit observation of the later 
symptoms, other than an occasional contortion of the bodv, the 
voiding of soft, watery feces, spewing at the mouth, and finally the 
complete loss of control of the legs. 
Since honeybees are extremely active and are easily studied in 
observation cases, they were fed arsenic acid (sample 10) in honey at 
the rate of 0.00076 milligram of arsenic oxid or 0.0005 milligram of 
metallic arsenic per bee, providing all consumed equal quantities of 
the poisoned food. The poisoned bees lived for 5.4 days on an average, 
while the controls lived for 8.4 days on an average. On the second 
day after being poisoned many of these bees became more or less 
inactive, a few died, and subsequently but few of them were seen 
eating. By the third day they were dying rapidly, their abdomens 
