6 BULLETIN" 256, U. S. DEPARTMENT OF AGRICULTURE. 



winter rains. If, however, the leaves are kept perfectly dry, a large 

 percentage of the nymphs fail to extricate themselves from the egg- 

 shell. This observation suggests the possibility that the species 

 may successfully pass the winter in the egg stage even in deciduous 

 leaves and in its most northerly range, provided these leaves are 

 sufficiently protected from freezing by a covering of dead leaves and 

 snow. 



INCUBATION PERIOD. 



Eggs have never been observed to hatch during the year they were 

 deposited, and in the San Joaquin Valley they invariably pass the 

 winter in the leaves on the citrus tree. The average duration of the 

 egg stage, as determined in 1911 and 1912 from 68 eggs deposited 

 between July 14 and August 6, was 286 days. Eggs deposited in 

 July averaged about 290 days; those deposited in August, about 275 

 days. Those deposited later in the year undoubtedly have a shorter 

 duration, since the period of hatching for all is short. In general, 

 the incubation period lasts from the maximum period of deposition, 

 about the middle of August, to the maximum period of emergence, 

 which, in 1912, was about the middle of May, or 275 days. 



• ENEMIES OF THE EGG. 



A small chalcidid parasite, determined by Mr. J. C. Crawford as 

 belonging to the genus Anastatus, is the most important, and indeed 

 the only enemy of the egg discovered during the investigation. 

 This parasite, though perhaps the most important natural check to 

 the species, is much more effective in checking the angular- winged 

 katydid, to which it largely confines its attacks. On March 22, 1912, 

 a quantity of orange leaves, each containing one or more eggs of 

 S.furcata, was gathered and kept in condition for the hatching of the 

 eggs. On April 2 adult parasites began to emerge from these eggs 

 and continued to do so for one and one-half months, or until May 18. 

 The proportion of eggs parasitized in the lot under observation was 

 25 per cent. The eggs were taken at random from all parts of an 

 orchard, and it seems reasonable to assume that fully 25 per cent of 

 all the eggs in this orchard were parasitized. 



General appearance of adult parasites. — The little parasites run- 

 ning over the orange leaves resemble small, winged black ants. 

 They are very active, glossy black, reflecting metallic bronze-green 

 in the sunlight. They have two pairs of membranous wings, the 

 fore pair in the female being almost covered by a large, brownish 

 spot; both pairs are transparent in the male. The female is about 

 one-eighth inch long, the male considerably smaller. Only one 

 parasite issued from a single katydid egg in any case observed. The 

 insect escapes from the side of the parasitized egg. The oviposi- 

 tion of Anastatus has not been observed. 



