96 INJURIOUS INSECTS OF 1909 AND IQIO. 
five specimens by sweeping this field. Most of these were winged. 
On June 2d he collected seven winged and one nearly mature wing- 
less specimen of this species, and on June 4th, he collected four 
winged and one wingless by sweeping. On June goth he collected 
one winged and one-half grown nymph by sweeping with a collec- 
tor’s net. There had been recent rains, and insects of all kinds were 
scarce on the rye on this date. On June 12th three winged and 
one wingless Macrosiphum were collected. On June 14th a con- 
siderable amount of sweeping failed to collect any specimens. On 
June 15th twelve wingless forms were found by sweeping. On 
June 21st seven wingless forms were found, but no winged forms. 
On June 25th a dozen wingless forms in all stages, and one winged 
adult were found, and on this date the first colony was discovered 
by examining the rye without the aid of the collector’s net. After 
this the rye was examined and swept from time to time with about 
the same results as before, only a very few specimens being found, 
and on July 24th, the rye having been cut on July 21st, the field 
was examined for the last time. The stubble was swept with a net 
thoroughly, but we were utterly unable to find any Macrosiphum. 
The shocks of rye and stubble were perfectly dry at this time. 
The fact that so few Macrosiphum appeared in this field after 
the heavy infestation of the previous fall, and the fact that we were 
unable to rear any specimens from the sod and earth brought in from 
this field in a cage in the insectary, leads us to have some belief in 
the theory that this species comes in from the South every year, and 
that it does not pass the winter in Minnesota in any form. The 
early date on which it was found would make it seem probable that, 
if it does come in this way, it is brought in from long distances by 
winds. But if this is the case it must have been brought in, this 
season, in rather small numbers, as the numerous sweepings in 
the rye-field indicate. 
On April 15th two shields of canvas, each 5x8 feet, were placed 
on the water-tank of the Experiment Station. In this position they 
were sixty feet above the ground, and as the tank is located on a 
hill, they were considerably higher than most of the surrounding 
country. These shields were covered with tree tangle-foot. The 
purpose of placing the shields in this position was to find out what 
sorts of insects were carried by the wind in considerable numbers, 
and to discover if Macrosiphum was among them. The shields 
were examined from day to day until July 6th, when the tangle-foot 
