THE MUSSEL SCALE. 23 



Reaumur was the - first to record the curious process of ovi- 

 position, or egg-laying, in an allied species, A. chelidonii. The 

 female fly first inserts her beak into the tissue of the leaf, and upon 

 this she swings round, depositing her eggs in a circle. This, how- 

 ever, does not always take place, for I have more often noticed the 

 -eggs in irregular groups of from seven to nine, or scattered singly 

 over the surface of the leaf. 



The eggs are tiny, smooth, shiny, elongate ovate bodies, almost 

 white when laid, with just a faint tinge of green, but in three or four 

 days they darken, changing to a bluish-black. They are attached to 

 the under side of the leaf by a short stalk from the broad end of the 

 ^gg. Specimens under observation indoors hatched out on the 

 ninth day after deposition, but out of doors twelve to fifteen days 

 is the usual period. 



The newly-hatched insect or pupa is about a quarter of a 

 millimeter in length, oval in outline, and when looked at from the 

 dorsal side as it lies upon the under surface of the leaf is seen to 

 have two caudal setae posteriorly and a pair of antennae anteriorly. 

 Looked at from the ventral side, three pairs of short, ill-defined 

 legs can be made out, a pair of large eyes, and between them and 

 ventrally a long, sucking mouth-tube, while posteriorly seven or 

 eight segments are fairly well marked. 



After a short time these pupae become attached to the leaf, 

 forming a peculiar skin which much resembles a scale insect. 

 Within the nymph changes to the fly. Later the dorsal wall splits 

 along the median line and transversely along a caret-shaped line, 

 -and the perfect insect escapes. The old pupal skin remain^ 

 attached to the leaves for some length of time. 



REMEDIAL MEASURES. 



The most satisfactory results have been obtained by fumi- 

 rgating with hydrocyanic acid gas. 



For spraying, almost any of the Aphis washes, are suitable, 

 TDut, owing to the difficulty in reaching the under side of all the 

 leaves, sprayfluids have not proved very effective. 



Very good results have been obtained by placing tarred and 

 newly- varnished boards and sticks amongst infected plants. 



THE MUSSEL SCALE. 

 Mytilaspis pomorum, Bouche. 



This insect is still far too common in our fruit orchards. 

 Considerable headway has been made in inducing owners 6T two 

 or three or single infected trees to spray the same with the soda and 

 potash sprayfluid. 



As pointed out in my last Report ^p. 19), wherever the scale 

 :is noticed the trunks and main branches should be well washed 

 with soda and potash (caustic alkali), and early in June sprayed 



