Jan., 1908.] Notes on the Aphididae. L 249 



believe that their production is dependent on either cHmatic 

 conditions or changes in the food plant. At present further 

 experiments are being conducted along this Hnc. So far as I am 

 informed this species has never been described or the peculiar 

 adaptations of its structure to its semi-aquatic life noted. 



Ohio State University, Columbus, Ohio. 



Note. — Since this paper was written specimens have been 

 received from Professor R. A. Harper, of Wisconsin State Uni- 

 versity which prove to be identical with this species. Professor 

 Harper reports them very troublesome on a number of water 

 plants in the University green house. 



EXPLANATION OF PLATES. 



A. — Nymph of apterous viviparous female before first molt. 



Fig. 1. Dorsal outline of head and thorax, showing antennae, 

 compound eye, thoracic tubercle, and the three thor- 

 acic wax glands. B. & L. 1 in. — f in. 



Fig, 2. Dorsal outline of the posterior region of abdomen showing 

 honey-tube within which are sinall characteristic 

 bodies and a fine tube which resmbles a trachea. Also 

 the two abdominal tubercles, their accompanying 

 hairs and the anal plate. B. & L. 1 in. — f in. 



Fig. 3. Sensory pits at base of unguis. B & L. 1 in. — ^ in. 



Fig. 4. Distal portion of tibia and tarsus, the former showing 

 the regular arrangement of the long hairs, and also 

 the pulverulent character of its surface. B. «S: L. 

 2 in. — ^ in. 

 ■ Fig 5 Dorsal view of insect. B. & B. 2 in. — 5 in. with lower 

 lens removed. 

 B. — Drawings of the adult apterous viviparous female. 



Fig. 6. Outline of head showing adult form of Fig. 1. B. & L. 

 1 in. — f in. 



Fig. 7. Outline of abdomen showing adult form of Fig. 2 with 

 Cauda developed. B. & L. 1 in. — | in. 



Fig. 8. Adult apterous viviparous female. B. & L. 2 in. — | in. 

 with lower lense removed. 

 C. — Drawing of adult winged viviparous female. 



Fig. 9. Outline of head showing ocelli and antennal sensories. 

 B. & L. 1 in.— I in. 



Fig. 10. Abdomen of above. B. & L. 1 in. — § in 



Fig. 11. Adult winged viviparous female. B. & L. 2 in. — f in. 

 with lower lense removed. 



Nott;. — The above drawings were made with the use of the camera 

 lucida at table distance. A Bausch and Lomb microscope was used 

 with the combinations indicated. 



