2T 



on, which hatched inside and grew to maturity, not, however, kill- 

 ing the caterpillars till after the latter had transformed to pupae. 



"I have since learned that another Tachina fly has similar habits 

 of laying its eggs, the "Uji," which is very destructive to sillv 

 worm caterpillars in Japan. This is the only instance I have found 

 in entomological literature of a Tachinid laying its eggs otherwise 

 than directly on the host (caterpillar, grass hopper, or whatever 

 it is.) 



"The egg-laying habits and the life history of the "Ugi" {Uginiya 

 sericariae Rondani) were published in detail by Sasaki, in Journ. 

 Sci. Coll. Imp. Univ. Japan, 1886. The eggs are laid on mulberry 

 leaves, eaten by the silk worms; hatch in the digestive canal in a 

 few hours; the larvae bore thru its walls, feed on the ganglia for 

 a time; later enter the tracheal system and become located in a 

 sort of cup or sac, with the spiracles at the posterior end near a 

 spiracle of the caterpillar and the anterior end with the body cavity 

 where it is convenient to feed on the fat of the silkworm; when 

 fully developed the maggot forces its way out thru the skin of the 

 silkworm (or pupa, if it has pupated); enters the ground to form 

 its puparium, within which it remains thru the winter. 



"Chaetogaeclia uwnticola agrees with this in some parts of its 

 development. The eggs are laid on leaves as before stated. The egg 

 of Chaetogaeclia appears as a tiny black dot on a grass leaf. It is 

 .44 mm. long by .25 mm. broad, quite regularly ovate, shaped like 

 a hen's egg only somewhat flattened where in contact with the leaf; 

 smooth and shining black. A female dissected was found to have 

 several hundred of them in the uterus. Another female which 

 bred out in capavity, was dissected when several days old, to count 

 the eggs. The uterus contained 1066 eggs* which were black and 

 apparently ready for oviposition. The ovarian tubes, which are 

 numerous and collected into two ball-like structures, were full of 

 immature ova. Probably the majority that are laid are not eaten 

 by caterpillars; hence, the provision of such a large number is to 

 insure some of them being eaten. They are so small as to escape 

 being injured by the jaws of the caterpillars in biting off bits of 

 leaf, tho probably some are destroyed. They soon hatch in the 

 alimentary canal of the caterpillar and bore thru its walls to the 

 surrounding body cavity. If they did not hatch the same day they 

 would probably pass out with the excrement. A caterpillar which 

 had been fed with leaves on which quite a number of Chaetogaeclia 

 eggs (dissected from a caught female) had been spread, died after 

 5 days. It was dissected and 2 4 maggots of the parasite were 

 found inside. They were about 2 mm. long and were mostly locat- 

 ed in the head and anterior segments of the caterpillar. Other 

 caterpillars which had been similarly treated and had died, were 

 dissected and fewer maggots found inside. With so many maggots 

 there is not food enough for all, so the caterpillar dies too soon 

 before the parasites can become full-grown. Perhaps only those 

 caterpillars which have eaten but one egg, or have had but one egg 

 hatch inside of them, are able to survive till the maggot becomes 

 full-grown, and those having more than one maggot inside die too 

 soon, and thus the maggots themselves die; at any rate, I never 

 have reared more than one parasite per host, nor have I found more 

 than one puparium formed per host. 



* I have since counted 494 4 eggs from the uterus of one female. 



