242 [ DISEASES OF THE PEAR TREE 



sulphur). The best results are obtained by the winter 

 treatment, when the tree can be thoroughly whitewashed 

 with lime, twice or thrice between December and 

 February. 



The pear is infested by various scale insects, but 

 here it is only necessary to mention those which are 

 found on the pear in these Islands. Chrysomphalus 

 dictyospermi Maskell is often troublesome and is perhaps 

 the worst. Mytilaspis pomorum Beke is frequent on pear 

 trees growing in sheltered and shaded situations. It is 

 similar to Mytilaspis citricola, but smaller. Lecanium 

 Oleae L., the black scale, is often found on the pear grow- 

 ing near Citrus trees. Lecanium Piri Schrk. is nearly 

 spherical with brown markings and finely dotted black. 

 Ceroplastes Rusci is rather rare on the pear, but leery a 

 Purchasi Mask, is more frequent. Aspidiotus Hederae 

 is perhaps the most common of scale insects affecting the 

 pear, and is almost sure to be present on trees growing 

 in shaded situations, but does not appear to be half so 

 virulent as Chrysomphalus. Dactylopius Citri Sigr. is 

 common on the fruit, usually inhabiting the depression at 

 the calyx, or the depression around the stalk, or the 

 sides of the fruits which are in contact in the same 

 cluster. Against the scales the sulphur-lime lotion 

 applied in a strong solution (6 to 8 per cent) in winter 

 gives very good results. The mealy bug, Dactylopius 

 Citri, should be brushed off the fruit before taking it into 

 the fruit-room, otherwise it will multiply there and 

 besides disfiguring the fruit will exhaust it by sucking 

 its juices, and also soil it by the honey-dew which it 

 secretes abundantly. 



The Diptera include two species which are injurious 

 to our pear trees. Cecidomyia Piri Beke is a minute 

 gnat-like dark-coloured insect, not longer than i| to 

 2 m.m., with iridescent wings provided with dark hairs, 

 with a black thorax, and light red sides and abdomen. 

 The headless and footless larva of this insect inhabits the 



