34 



BULLETIN 265, U. S. DEPARTMENT OF AGRICULTURE. 



None of these parasites was reared from false-worms that had 

 bored into apples, which indicates that the parasites oviposit in the 

 worms, by means of their stout ovipositors, after the worms have 

 bored into the stems and formed their pupal cells. The parasites 

 would have little opportunity of ovipositing in worms in the apples, 

 even if they could reach them, since the apples are usually picked 

 and hauled away not long after they become infested. 



From the infested stems collected in 1915, a total of 261 insects was 

 reared, comprising 92 ichneumonid parasites and 169 sawnies. Thus 

 there was a parasitism of 35.2 per cent. 



CHALCIDIDS. 



In July and August, 1915, parasitized eggs of the dock false-worm 

 were taken near Wenatchee, Wash. These were black in contrast to 

 the light color of normal eggs. In due time a single small chalcidid 

 emerged from each through a small hole near one end. Specimens 

 submitted to Mr. J. C. Crawford were determined by him to be 

 Trichogramma minutum Riley, a minute chalcidid which parasitizes 

 eggs of various Lepidoptera and Hymenoptera, and often practically 

 annihilates its host, at least temporarily. Eggs of the sawfly were 

 collected at intervals from July 26 until September 8, and the amount 

 of parasitism determined. Eggs had been collected several times 

 previous to July 26, but none had been observed to be parasitized. 

 Table XXIV shows the percentage of parasitism. 



Table XXIV. — Percentage of parasitism of the eggs of the dock false-worm by Tricho- 

 gramma minutum, Wenatchee, Wash., 1915. 



Date of observation. 



Total 



Number 



number 



parasit- 



of eggs. 



ized. 



33 



13 



15 



3 



11 







28 



2 



158 



13 



23 



1 



268 



32 



Percent- 

 age para- 

 sitized. 



Julv26.... 



Aug. 2 



Aug. 16 



Aug. 23 



Aug. 30 



Sept. 8 



Total 



39.3 

 20.0 

 0.0 

 7.1 

 8.2 

 4.3 



11.9 



BRACONTDS. 



Kleine (1908) mentions a parasite of the dock false-worm in Ger- 

 many, which proved to be RJiysipolis sp., a braconid. 



PREDACIOUS ENEMIES. 



Since the dock false-worm is a soft-bodied larva, living unpro- 

 tected on the leaves of its food plants, it would be reasonable to sup- 

 pose that predacious enemies in the form of other insects or birds 

 would prey upon it. Only one such case has been noted, however. 



