59 BULLETIN 416, U. S. DEPARTMENT OF AGRICULTURE. 
determine the egg-eating capacity of Mycodiplosis, but from a few ! 
field observations we are convinced that its appetite is about the same 
as that of Arthrocnodaz carolina. 
SYRPHIDAE. 
Quayle (1913) states that there are two or three species of syrphus- 
fly larve that eat red spiders. Ewing (1914) also records that he 
has seen them feeding on the mites in hop fields. However, we find 
no records of any of these having been reared or specifically identified. 
At Batesburg syrphus flies are found in all stages in cotton fields 
from the last of May until the Ist of September, and are most 
abundant during Juiy and August. They are incidental enemies of 
the red spider, and are more intent upon the capture of aphids and 
insects More conspicuous than mites. However, they are often seen 
crawling through red-spider colonies, and upon a few occasions 
have actually been seen to devour adele mites. 
Baccha clavata Fab.—This dark-colored, wasplike syrphid was 
apparently the commonest species. The larve and the large, flesh- 
colored puparia could always be found through the midsummer on 
cotton infested with aphids and mites. A larva was seen to grasp 
and devour a female red spider in an interval of 2 or 3 seconds. 
Table XXI gives statistics on red-spider consumption gathered from 
tests with larve of Baccha clavata collected in the field in various 
stages of development. 
Taste XXI.—Red-spider consumption by larvxe of Baccha clavata, Batesburg, S. C. 
Consumption of mites.! 
Individual | 
No. ist | 24 | 3d | 4th | 5th | 6th | 7th | sth | 9th | 10th | Peed} Total 
ing |mites 
day. | day.| day.| day. | day.| day.| day.| day. day.| day. days.|eaten. 
eee = LS ae eae eee rn cate ey Le (esi avons he a Sai 1a 
Dir eee Se COPA 2 Ot ASE TS eee ee eee tebe tm yore Rees eso eerie 2 126 
BeOS Soe 60 | 33 47 2 26 13 21 | 27 | 20 - 10 | 253 
Seer PAN isk ae fle acer Pe S| Se 3 ema REY Fe el IO el [eg EN cc fete Ed | 1 
Bue ae 13, |, 110 TR ed me? Le aT eek Pare es ee We PA 
bird PES Sta EAE LA aE eel PRIS | EES ee 
pi Dg 3] meal Somme RAO) Pee Den been el es mel etal ee Re RS Shale Seka Mt ee ee 17 450 
i Fed with adult mites but many mite eggs were also eaten. 2 Pupated. 
It will be seen that 5 larve of Baccha clavata in 17 feeding days 
consumed 450 adult red spiders, which gives an average of 26.5 
mites per day. 
Allograpta obliqua Say.—This sre ee syrphus-fly, with 
abdomen alternately banded with sulphur yellow and chocolate 
brown, probably ranks second in abundance among these flies. Its 
larvee are seen commonly in fields durmg August. 
