8 OHIO EXPERIMENT STATION: BULLETIN 197 



i 



DESCRIPTIVE. 



Egg: The egg is elongate with rounded ends, being about .35 mm, 

 long and from one-fifth to one-fourth as wide as Jong. It appears trans- 

 lucent greenish or whitish, probably depending somewhat on the de- 

 gree of development reached. The eggs are laid in masses, a single 

 mass sometimes containing upwards of 80 eggs. Many of these 

 eggs are curved into a bow shape, and their sides adhere to each 

 other somewhat. The masses found were laid on the inner sur- 

 faces of the tiny young leaves just formed in the terminal buds. 

 Whether the larvae found on the older leaves come from eggs 

 scattered promiscuously over them, or if they disperse from egg- 

 clusters, deposited in the manner observed when the leaves are 

 young, we do not yet know; nor do we know where the eggs are laid 

 from which hatch the larvae found in the pods. 



Larvae: The full-grown larva is about one-eighth of an inch 

 long and about one-fifth as broad as long. The color varies from 

 pale whitish to orange. Those working most in the open, as upon 

 the leaves, seem, generally speaking, to be the deepest colored; yet 

 deep colored specimens may often be found in buds and also in 

 seed-pods. With a good magnifying glass the body is seen to be 

 segmented transversely, a compound microscope showing fourteen 

 segments. The larva possesses a peculiar habit. It brings the 

 two ends of the body together and by suddenly straightening itself 

 with a jerk, is enabled to jump several inches. 



Adult: The female is a minute, two-winged fly, about one-six- 

 teenth of an inch long and has a light yellow body and dusky wings 

 that show a bluish iridescence under a magnifying glass. 

 SUMMARY OF LIFE HISTORY AND HABITS. 



The adult flies must first appear in May, since the spots on the 

 leaves appear in that month or early in June. On June 22, 1908, 

 larvae could be found in abundance on the leaves and also in the 

 terminal buds. Adults could be seen here and there on the leaves 

 and could be captured in abundance by sweeping catalpas with a 

 net. Egg-masses, freshly laid, could be found in the terminal buds. 

 Cuttings of catalpa, containing hundreds of larvae, were sunk into 

 moist sand and placed in breeding cages. Adult flies appeared in 

 these cages July 4th, and for several days thereafter. It was 

 difficult to find a mass of eggs, part of which had not hatched at the 

 time of discovery, thus evidencing the shortness of the incubation 

 period. As nearly as we could determine from eggs laid by midges 

 in our cages, the young larvae begin to emerge within 24 hours or 

 less after the eggs are laid. As nearly as could be judged from our 

 breeding work, the life of a complete generation in mid-summer is 



