THE WATER-CRESS LEAF-BEETLE. 
(Phsedon aeruginosa Suffr.) 
By F. H. Chittenden, 
Entomologist in Charge of Breeding Experiments. 
INJURIOUS OCCURRENCE. 
Among plant-feeding native insects which have recently appeared 
in new roles is a little blackish leaf-beetle, Phcedon aeruginosa Suffr., 
which was reported for the first time as injurious to water cress 
(Nasturtium officinale) in Pennsylvania, in 1903. 
During September Mrs. Hannah B. Hannum, Brandywine Summit, 
Pa., sent larva? and adults of this species, with statement that they 
were devastating her water-cress pond. Both larva? and beetles fed 
chiefly on the lower side of the leaves. In confinement they con- 
tinued feeding, attacking the stalks also. The larvae all reached 
development about the same time, being fully matured September 11 
and 12, on the last of these two days crawling about the rearing jar 
and ceasing to feed. The pupal period was not observed, but it 
probably lasted ten days or a fortnight, as the weather was cool. 
The beetles continued for some time in our rearing cages, frequently 
pairing, but depositing no eggs. 
August 19, 1904, Mrs. Hannum sent additional specimens of this 
species in the beetle and nearly grown larval stages. It was noticed 
that the beetles did not swim rapidly, but steadily, and they were 
seemingly not discomposed by being somewhat out of their natural 
element. It seems probable that they fly from plant to plant, and 
like most beetles undoubtedly are able to float for many hours, and 
perhaps even swim short distances until they reach a landing place. 
September 13 our correspondent sent still another lot of this species, 
mostly beetles, but a number of larvae were included. 
Specimens of the larvae of a syrphus fly accompanied this sending 
and probably fed at times on the small larvae of the beetle. 
DESCRIPTIVE. 
The oeetle. — This species belongs to the tribe Chrysomelini of the 
family Chrysomelidae. It is classified in our publications on the 
Coleoptera of America north of Mexico with Plagiodera, but Eu- 
ropean systematists place allied forms in the genus Phasdon Latr., 
which now comprises seven species occurring in our country. They 
are very small semiglobose forms. The outline is oval, with the thorax 
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