ILLUSTRATIONS 



PLATES 



Life History op Plutella maculipennis, the Diamond-back Moth 



Page 

 Plate i.-A. — Plutella maculipennis: Adnlt. B. — Plutella maculipennis: Lar- 

 va. C. — Puiella maculipennis: Pupa. D. — Leaf of mustard, shomnj 



injury by Plutella maculipennis lo 



Plate 2. A. — Angitia plidcllae, parasite of Plutella mactilipennis. B. — Spi- 



lochalcis delira, a parasite on Angitia plutellae 10 



Daily Variation of Water and Dry Matter in the Leaves op Corn 

 AND THE Sorghums 



Plate 3. Milo, com, and kafir leaves, illustrating the method used for obtaining 



the leaf samples for the determination of the v/ater and dry matter 46 



A New Disease op Wheat 



Plate 4. i, 2. — Spikes magnified to show more distinctly the dark blotches 

 and stripes which are signs of the disease. 3. — Outer surface of a leaf 

 sheath showing black spots and stripes occupied by bacteria 54 



Plate 5. Spikes magnified to show black stripes on glumes and awns 54 



Plate 6. i. — Black stripes on glumes, awns, and rachis. 2. — Spikelets aborted 

 and blackened, awns twisted, rachis badly diseased (blackened or water- 

 soaked in appearance and oozing bacteria) 54 



Plate 7. i. — Rachis black and oozing honey-yellow bacterial slime Avhich 

 dries as pale yellowish or whitish crusts. 2, 3. — Same disease on upper 

 part of culm showing as dark spots or stripes oozing pale-yellow masses of 

 bacteria 54 



Plate 8. Shriveled kernels from a single head of wheat like those sho^vn on 



Plate 4. Not one berry is plump, and many are badly shriveled 54 



A Further Contribution to the Study op Eriosoma pyricola, the 

 Woolly Pear Aphis 



Plate 9. A. — Eriosoma lanuginosa: Distal segments of antenna of spring 

 migrant. B. — Eriosoma pyricola: Distal segments of antenna of spring 

 migrant. C. — Eriosoma pyricola: Distal scgmentsof antennaof fall migrant 

 from European pear stock. D. — Eriosoma pyricola: Distal segments of 

 antennaof fall migrant, American material. E. — Eriosoma pyricola: Distal 

 segments of antenna of spring migrant 74 



Plate 10. Eriosoma pyricola: A, D. — Galls containing fourth-instar stem 



mothers. B, C. — Mature galls. E. — Old gall 74 



Isolation op Cyanuric Acid prom Soil 

 Plate ii. Cyanuric acid isolated from Indiana soil 92 



A Needle Blight op Douglas Fir 



Plate 12. A. — The needle-blight fungus as it appears normally infecting the 

 i-year-old needles of Pseudoisuga taxi/alia. B. — An 18-3'ear-old Douglas 

 fir, showing the thin foliage due to infection with the needle-blight fungus . 104 



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