79 



MISCELLANEOUS INSECTS INJURIOUS TO VIOLETS. 



A perusal of available literature shows some additions to be made to 

 the list of the different species of insects which have been treated in 

 preceding pages in connection with their attack upon the violet, and 

 some insects are also mentioned in the files of this office, which have 

 not been recorded as attacking this plant. 



"Green ApMs."— Two and probably more species of aphides affect- 

 ing violets are known to growers, but only two have been identified 

 specifically. These are the plum plant-louse, Myzus mahaleb Fonsc. , 

 which was treated on pages 52-59, Bulletin 7 of the present series, 

 and BJwpalosvphum dianthi Schrank. The first of these was received 

 November 19, 1898, from Mr. W. D. Philbrick, Newton Center, Mass., 

 who stated that these plant-lice were usually noticed to be quite plen- 

 tiful when the violet plants were first brought in under glass in the 

 fall from the field where they are grown in the summer. This form is 

 usually found on the underside of the large old leaves near the ground. 

 During January and February, 1899, specimens were received from 

 Mr. F. B. Boone, Charlottesville, Va., found on violets grown under 

 glass. May 2, of the same year, Mr. Gallowa}^ brought specimens 

 which were present upon violets, Scrophularia and Capsella bursa- 

 pastoris, at his place. 



A comparison of the nature of injury by the green aphides which 

 attack violet and the brown or black aphis is made by Mr. A. F. 

 Woods in a statement that the latter produces a marked stunting of 

 the plants, while the former does little injury outside of distorting 

 the flowers (Bui. 19, Div. Veg. Phys. and Path., p. 21, 1900). 



Rhopjalosiphum dianthi Schrank. was received November 21, 1898, 

 from Mr. W. C. Pray, Kinkora, N. J., who sent two apterous specimens 

 found upon violets at his place. These plant-lice were described as 

 causing the flowers to turn white in spots by suction of the juices from 

 the parts affected. 



The "syringing," or, more properly speaking, spraying, to which 

 violet plants are subjected two or three times a week to keep them 

 free from "red spider," also serves to suppress or to at least keep 

 down the number of aphides, and it is perhaps this remedy more than 

 anything which has held in abeyance the so-called green aphides of 

 violets. 



A scale insect on violets. — A scale insect known as Dactylopius 

 mrgatus is on record as attacking violets (Insect Life, Vol. V, p. 247). 



Butterfly caterpillars. — A considerable number of butterflies of the 

 genus Argynnis subsist in the larval condition on wild violets, which 

 is their normal food plant, and these and related species which attack 

 wild violets are liable at any time to attack cultivated plants. Among 

 related species which have similar habits is Melitwa editha Boisd. 



