42 



probable that some of our native species would acquire a taste for this 

 pest, and this species, which Mr. Loomis sends, is confirmatory of our 

 surmise. The Ocneria has evidently been imported into Japan from 

 Europe and as the parasite which he sends can not be identified with 

 any of the known European parasites it is probably a Japanese insect 

 which has learned to prey upon the Ocneria. The parasite is an Apan- 

 teles and seems to be a new species. The Microgasters, by the way, 

 seem very fond of this larva as our list in the article above referred to 

 embraces no less than nine species which prey upon it in Europe. 



TheOvipositionoftheHornFiy.— In regard to the egg-laying by the 

 Horn Fly, Prof. J. B. Smith (in his annual report for 1889) takes direct 

 issue with us upon the point as to whether the eggs are laid during the 

 day or during the night, a point of considerable practical importance 

 in view of its bearing upon remedies. 



We have carefully searched through Professor Smith's account, and 

 the only definite observation which he has recorded is that flies put in 

 a large bottle with fresh cow-dung rested quietly upon the glass and 

 upon some chips which he had also placed in the bottle and had not 

 oviposited "early that evening ; i. e., 8 o'clock. Next morning the flies 

 were still alive, and there were numerous eggs on the chips, on the sides 

 of the bottle, and on the top of the manure." He also quotes Mr. Bodee, 

 of Freehold, to the efl'ect that the eggs are laid at night, and in fresh 

 droppings. On the strength of these premises, and ignoring the fact 

 that cows normally drop no dung from the time when they lie down at 

 night until they arise at daylight. Professor Smith disputes the force of 

 the positive observations detailed in our article on pp. 93-103 of Vol. II. 



These observations by Mr. Marlatt, as there stated, were made in the 

 field upon the natural process of oviposition. From these observations, 

 repeated a number of times, and from the long course of field study, 

 both by Mr. Marlatt and Mr. Howard, there can be no doubt but that 

 the eggs are normally laid only at the moment of the dropping of the 

 dung. Mr. Marlatt's observation that, the number of eggs laid in dung 

 dropped between sunrise and 7 o'clock compares with those laid in the 

 hot sunshine between 10 and 11.30 only in the proportion of 10 to 350 

 is conclusive against Professor Smith's position. We consider that our 

 generalization to the effect that " the eggs are deposited during day- 

 light, chiefly during the warmer time of the day, between 9 and 4, and 

 mainly between 9 in the morning and noon," is more than substantiated 

 by recorded observations and is not vitiated in the least by the action 

 of frightened flies coutined in a bottle, and which from Professor Smith's 

 own statement (and from our own experience frequently repeated) de- 

 parted so far from their normal habit under these unusual conditions as 

 to oviposit upon chips and glass. The statement, however positive, of 



