69 
The condition of the Hessian fly in these three plats, at the time of 
harvest, July 10, 1888, may be inferred from the result of examinations 
made on this date. 
EMD bys WAxXseedS) oe acs aoc selene. seieasa sao spews cis ec em ajetsccrcinae 15 
Containing healthy pups or parasites....-...---.---..-----.----. 69 
Vcore aeiotemae tesciceisl see ee eee ee ee cinae eens Seis ssivinieilainisiasiacie 16 
MNO lial leet eee oie aetaia at ste an ote inte a cnete sieteraetnainin wii Seteicin ofeimicieiel Seale 100 
August 3, the state of the insect in these same plats was as follows: 
lava DUN; HEREC ae Gok cipap nde DOOODE DHS AOO Hebe Dns DEDPCurCCD eoDooc 53 
Containing healthy pups and parasites.......-..---------- --<-0< 47 
otal nes clase osc e tiew estas clavseryee ciate cis shacieia, clecisleais's sistae esis 100 
The condition of the insect on September 1, as shown by examination 
of the stubble, is indicated below: 
PM yp AXSCOOS cme cibre ee esine ae eleaae cece = cco were siclecerse ain nee aeate 55 
Healthystlaxsecdshiscecccce arse cee nse ne epee cel aw ae sae an oe eaaete 28 
RaTARILIZeO HaXBOOGS = ase ete om eee ol ost e an ete ne eeoetosetes oe 17 
: Saye BAS are MTA ga EM ot EL VM Sea me A IR RE 100 
Notwithstanding the per cent of healthy puparia passing the summer 
was small, there is little probability that many adult flies emerged. 
A plat of the same dimensions was sown July 16, along one side of the 
first three sown the previous fall, the plants of this last sowing coming 
up ten days later. This plat was closely watched. After July 17 only 
an occasional larva was found. By August 4 plants had been de- 
stroyed by the combined influences of chinch bugs and dry weather, 
but a second plat has been sown adjoining, and the plants of this ap- 
peared above ground on August 6. On September 4, 200 plants were 
examined and but two larveze were found thereon. A second examina- - 
tion of the same number of plants from this plat, on September 15, re- 
vealed a small number of young larve. ‘A third examination of this 
plat on October 6 showed about 1 per cent of the plants to be infested. 
Stubble from the three original plats, keptin breeding cages, out of doors, 
did not give adults until the 17th of September, although it is quite 
probable that some few were abroad before that date. It will be seen, 
however, that no great number could have emerged from the stubble, 
and the increase in the number of empty flaxseeds between July 10 and 
September 1is doubtless to be attributed to parasites. This appears all 
the more probable, as I have repeatedly observed these parasites 
during July and August emerge in breeding cages, and at once begin 
to oviposit in flaxseed in the stubble from which they had themselves 
emerged. The percentage of healthy puparia reaching September in 
safety, however, was probably unusally small, as experiments on the 
same ground the following year did not suffer near somuch from either 
fall or spring attacks. Another feature of these experiments is, that 
it strongly indicates that the larger per cent of the parasites emerge 
prior to the 1st of August. Indeed, stubble from the entire length of 
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