INSECTS AND OTHER ANIMAL Pests InsuRIOUS To FIELD BEANS 961 
The season of 1920 varied little from the two preceding years. The 
first flies were found on May 7, some containing eggs that were partly 
developed. Most of the eggs of the first brood were deposited during the 
first week of June. Eggs of second-brood flies were deposited early in 
July. The relationship between the time of oviposition and the dates of 
bean planting is discussed later (page 972). 
The larva 
Length of larval stage 
The average length of the larval stage for eight specimens of Hylemyia 
cilicrura, which had been bred in vials in a field cage at the Perry laboratory 
in 1917, was 10.4 days, with a variation from 8 to 12 days. The data are 
given in table 2: 
TABLE 2. Breepinc Data For Eraut Fires Rearep In 1917 
Length Date of Length Date of Time 
: of larval | beginning | of pupal | emergence | from egg 
Date of hatching stage of pupal stage of to adult 
(days) stage (days) adult (days) 
Illy 176053 5 12 July 29 20 | August 18 32 
JURA 364 6 Soe Bee eee oe ee ila July 28 14 August 11 25 
Jal? USS 3.c.5s 6 Seale tol roe eee eee 12 July 30 11 August 10 23 
Telly 2sis ob tonn sos See 8 August 2 10 August 12 | IZ 
Talk, 2, oo ce oc dee oe eee 10 August 4 12 August 16 22 
TROUT AD ions cals Siva d Oo ae eee 9 August 4 12 August 16 21 
Uwlhy AO va bic eocen eRe 9 August 4 16 August 20 25 
JRaP AGS sio's 5 ue ota eae ee | 12 August 6 15 August 21 27 
A STCTEIGD) doda.d gn ese ere ee TCO Y3e: Sra aaa ae Ree 1 SReie |e 24 
In June, 1919, the average larval period in the case of twenty-one 
first-brood maggots bred in the laboratory at Perry, was 9.4 days, with 
a range from 7 to 12 days. Specimens bred in the field cages required about 
two days more. 
Habits of the larva 
The larvae of Hylemyia cilicrura are instinctively internal feeders. 
When they hatch, the small larvae crawl thru the crevices of the soil in 
search of food. In this search they show a preference for material that 
is beginning to rot, and they are always most numerous in decaying beans. 
Seventeen maggots were once found in a slightly decomposed bean, and 
seven to ten is not an uncommon range. They may be found in sound 
