INSKCT ENEMIKS OF THE CODLING MOTH. 24I 



The Development of Trichograrnmatoidca liitea in a 

 Codling Egg. — Several codling mollis were enclosed in a bell-jar 

 with glass slides upon which rested small pieces of cotton, soaked 

 in sugar and water solution to attract the moths to the slides. 

 Three codling eggs, marked (a), (b), and (c) respectively, were 

 laid on the glass slide on the night of February lo. Several 

 parasites were placed on February 12 in a glass tumbler, to- 

 gether with the three eggs on the slide. A parasite was seen 

 ovipositing in egg {c) on the morning of February 13, after 

 which the parasites were removed. Eggs of the parasites were 

 indistinctly visible as minute oval forms in the codling eggs 

 when they were examined with the microscope on the night of 

 February 13 by means of reflected artificial light (see Plate XX). 

 The appearance of the codling eggs and the development of 

 parasites within them are indicated in the following diary, and 

 observations as seen through the microscope are illustrated in 

 the drawings of Plate XX showing egg (a) much enlarged. 



February 13. 9 p.m.- — As illustrated in Plate XX {b), repre- 

 senting codling egg (a), each codling egg has five concentric 

 circular areas, the outer comprising only the transparent shell 

 with irregular netted ridges. The middle circular area is com- 

 posed of opaque more or less pentagonal cells filled with an olive- 

 coloured granular substance, and bordered on the inner margin 

 by an irregular circular ring of red pigment. The inner area is 

 almost as light and transparent as the outer ring, and contains 

 cells similar in texture to the middle area, but not so closely 

 packed, and hence more spherical. In the middle area of (a) 

 are five indistinct minute oval olive-coloured eggs, three in {b), 

 and two in (c). These are the eggs deposited by the parasites. 

 Others possibly are present, but are not visible. 



February 14, 9 p.m. — ^Codling egg (a). See Plate XX (c). The 

 eggs of the parasite have hatched in the codling egg, thus show- 

 ing that eggs of T. Intea hatch in about 24 hours or less. The 

 parasite larvse are eight in number, four distinctly larger than 

 the others. They take up the whole of the central and middle 

 circular areas as described above, so that now there appears to 

 be only two circular areas in the codling egg, an inner and an 

 outer zone. The red granular pigment has now become dis- 

 tributed in small quantities, and forms practically an outer 

 border for each larval parasite. The pigment is evidently 

 absorbed by the parasites. The larvse, viewed through the 

 codling egg-shell, are more or less rectangular in shape, owing 

 apparently to pressure. The embryo cells of the developing 

 codling larva, as described in the codling egg February 13, have 

 disappeared, and the parasites appear as granular olive-shaped 

 masses of small circular cells, practically immovable except at 

 the narrower or head end, which sways slightly laterally, and has 

 a pulsating movement. The head end of one lies by the head end 



