8 BULLETIN 902, U. S. DEPARTMENT OE AGRICULTURE. 
When the beetles occur in great abundance they injure also sugar 
beets and table beets (Beta spp.), mangel-wurzel (B. vulgaris var. 
macrorliiza) , lettuce (Lactuca sativa). beans (Phaseolus spp.), peas 
(Pisum sativum), carrots (Daucus carota) , tomato (Lycopersicum 
esculentum), potato (Solan um tuberosum), and corn (Zea spp.). 
Injury is due to the beetles eating pitlike holes in the leaves 
of young plants, usually selecting the lower surface. Eadish is so 
seriously attacked practically everywhere within the destructive 
range of this pest that it is almost impossible in such regions to grow 
this vegetable unless strenuous efforts are made to prevent the inroads 
of the flea-beetle. Turnip and mustard are about equally attractive 
to the beetles and unprotected beds are frequently destroyed. Impor- 
tant injury to cabbage is confined to young plants in seedbeds or to 
plants soon after they have been transplanted in the field. Horse- 
radish is readily attacked and the foliage is often so completely 
riddled that it has the appearance of a sieve when held up to the 
light. This plant, however, is very resistant and the roots attain a 
good growth in spite of severe attack to the leafage 
The larva? have been observed on radish. Cleonie, and Lepidium 
pubecarpum only, but doubtless live on the roots of many other 
cruciferous and related capparidaceous plants. The injury done 
by the larvae is negligible, so far as our observations go, in which 
respect this species differs from the related striped cabbage flea- 
beetle and horse-radish flea-beetle. 5 
SEASONAL HISTORY. 
In its more northern range the beetle passes the winter months 
in hibernation under clods -of earth, or under heaps of weeds, dead 
leaves, or other rubbish, whence it comes forth with the first warm 
days of spring. In the extreme South the beetles are active through- 
out the year but reproduction does not occur during the winter. 
In the Arkansas Valley the beetles issue from their winter quarters 
during the latter part of March or early April. At first the foliage 
of Sophia pinnata and horse-radish supply them with food. From 
these plants they go to early mustard and radish, and throughout 
the season or until severe freezes have occurred the beetles are to be 
found on various cruciferous vegetables and weeds. In south Texas 
beetles occur afield from February until December, being found, with 
the exception of two months, practically throughout the year. 
There are apparently three generations annually in Otero County, 
Colo. Egg laying begins within a few days after the beetles leave their 
winter quarters — as early as April 14 — and continues until early 
September. 
5 Phyttotreta vittata Fab. and Ph. armora-ciae Koch, respectively. 
