Jan., 1908.] The Ohio Species of the Genus Disonycha. 
423 
THE OHIO SPECIES OF THE GENUS DISONYCHA.* 
Leonard L. Scott. 
The genus Disonycha is a small group of beetles belonging to 
the family Chrysomelidae. They are generally distributed 
throughout the United States but are abundant only in certain 
sections, where they may become of some considerable economic 
importance. Certain species are distinctly southern in distribu¬ 
tion, others are found more commonly in the arid portions of the 
country, while still other species may be found only in sections 
that are under cultivation. The species seem to possess, to 
quite a marked degree, the ability to adapt themselves to 
widely varying environmental conditions and this fact may be 
responsible for their very general distribution throughout the 
country. The food plants of the group as a whole are mostly 
herbaceous although some species may be found feeding on 
shrubs or even on forest trees. Several species are frequently 
reported as doing a very considerable amount of injury to the 
leaves of sugar beets and spinach, the latter becoming so badly 
eaten as to be unsalable. Lambs-quarter and spiny pigweed are 
also favorite food plants, but since these plants are not of eco¬ 
nomic importance, the injury done to them is beneficial rather 
than injurious. Two species reported from New York were 
found quite generally on the common arrow-head, Sagitarria 
variabilis and also on beets, spinach, Chenapodium album and 
Amarantus spinosus. 
Some peculiar habits of the group are worth mentioning. In 
the first place in several of the species upon which observations 
have been made, the adults and larvae feign death and fall to the 
ground when suddenly disturbed, although if the approach is 
made quietly, the adults will either not move or will take wing 
and fly to another plant. On account of this habit, the cause of 
the injury to beet-leaves and the like is frequently not observed 
and may be attributed to other insects. D. quinquevittata has 
been observed (Ref’s. 3, 7) swarming near Yuma, Arizona. 
About three o’clock in the afternoon an immense swarm, prob¬ 
ably 20 or 25 feet thick, was observed passing up the Colorado 
River, following quite closely the bed of the stream and flying 
about 50 ft. above the water. When insects migrate, it is usu¬ 
ally on account of a lack of food, but since there was an abund¬ 
ance of food present in this instance the migration may have 
been caused by the peculiarly sultry condition of the atmosphere 
at this time; this is frequently a cause of migration in other 
groups of insects. Reports of migrations of this species are not 
known from any other section of the country. 
Although the group has been known for a long time and more 
or less work of a general nature has been done upon the various 
|R * Read at the meeting of the Ohio Academy of Science. 
