90 
IOWA ACADEMY OF SCIENCES. 
ECONOMIC CONSIDERATIONS AND REMEDIES. 
Working as these forms do, on the roots of grasses, their 
injury is not noticed. The form that infests annual grasses is 
of but little economic importance unless they are transferred to 
corn by ants. Thorough cultivation will check this tendency, 
as the ants do not like to have their formicaries disturbed, and 
doubtless a proper rotation of the corn crop would avoid most 
of the injury. Though the perennial grasses, on which the 
migratory forms were most commonly found, are not used much 
in some parts of the state, they are the best native grasses we 
have. In localities where they are used the vitality must be 
greatly reduced by the juices being pumped away from the 
roots by these small pests. If timothy proves to be commonly 
infested, the importance of the pest is great. The most practi- 
cal remedy at present seems to be the destruction of the worth- 
less Dogwood shrubs. Spraying in the spring with kerosene, 
emulsion, would be effectual if these shrubs were not scattered 
around in every hedge row and fence corner in the country, but 
as the Dogwood possesses no value except possibly in some 
instances as an ornamental shrub, it would seem the part of 
wisdom to destroy them entirely. They should be cut up from 
the roots in late autumn, in winter, or early spring (at latest 
before blossoms open), and burned. 
SUMMARY. 
Schizoneura corn! spring migrant failed to colonize artificially . 
on annual grasses. 
Schizoneura panicola failed to colonize artificially on Cornus 
when transferred in autumn. 
Schizoneura from perennial grasses gave fall migrants that 
colonized readily in numbers when artificially transferred. 
There are two, if not three, distinct forms on roots of grasses, 
one occurring mainly on perennials and migrating in autumn to 
Cornus, the other occurring on a variety of annual plants and 
remaining for the most part under ground, but depositing eggs 
each season, while the third hibernates in chambers of ants. 
Schizoneura corni, root form, occurs on wild grasses and. 
probably timothy. 
