﻿48 BUIXETIN" 1147. U. S. DEPARTMENT OF AGRICULTURE. 



Table 22. — Arsenic consumed by insects in feeding tests, 1919 — Continued. 



Species of insects 



Arsenlcals and controls. 



Condition of 



larvee beforo 



being analyzed. 



Num- 

 ber of 

 larvos 

 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 



150 

 125 

 100 

 150 

 110 

 80 

 110 

 130 

 100 



100 



120 

 130 



Milli- 

 grams. 

 0.0017 



.0020 



.0038 



.0026 



.0043 



.0042 



.0049 



.0029 



.0028 



.0018 



.0024 

 .0051 



141 

 168 

 327 

 205 

 311 

 330 

 350 

 223 

 257 



172 



206 

 460 





62.1 



28 



do 



do 



53.4 



6S 



57.9 



5 



do 



62.7 



69 



do 



61.8 



69B 



do 



61.9 



71 



do 



50.9 



62 



do 



57.1 



55 



do 



51.8 



23 



do 



54.7 



64 



do 



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 ARSENIC 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 body, 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 oi 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 



