188 D. d'emmerez de charmoy and s. gebert. 



products will rank among the chief of our minor industries. Preserved limes are 

 imported from Rodrigues, a dependency of Mauritius, where the trees bear good 

 crops. The crop obtained there is, in fact, too large for the wants of the island, 

 and the excess is salted and sent to Mauritius. Other citrus fruits, such as mandarines, 

 oranges, lemon, shaddock, etc., also grow well and give good returns, so that on the 

 whole the group is of increasing importance locally. 



There are many insects that attack these plants, the chief pests being Papilio 

 demodocus and the citrus aphis. 



Papilio demodocus, Esp. This butterfly, which is known all over Africa as an 

 enemy of citrus trees, is here a most troublesome pest to young plants. The cater- 

 pillar destroys the seedlings when they are three or four inches high, and if removal 

 of the larvae from young plants is not practised constantly, considerable damage 

 is done. No great injury is done to full-grown plants. The eggs and larvae are very 

 conspicuous and can be easily removed from seedlings by hand-picking. 



Papilio phorbanta, L. The life-history and habits of this butterfly are much 

 the same as those of Papilio demodocus. It is less common than the latter and 

 can rarely be reckoned as a serious pest of seedlings. The eggs are always laid on 

 the lower surface of tender leaves ; Papilio demodocus, on the other hand, seems 

 to deposit its eggs anywhere. 



The scale-insects found on lime trees are eleven in number and occur in abundance 

 during the beginning of summer. When the rainy season sets in and the air becomes 

 saturated with moisture, the scales are to a great extent attacked by several parasitic 

 fungi, which gradually destroy them. This statement does not, however, always 

 hold good for the coastal regions, where the heat is excessive and the climate com- 

 paratively dry. It is especially there that the presence of scale-insects is felt, for 

 the damage caused is appreciable and the scales occur all the year round. The ten 

 species found are : — 



Chrysomphalus aurantii, Mask., and Chrysomphalus ficus, Ashm., on the twigs 

 and stems. 



Pseudaonidia trilohitiformis. Green, on the leaves. 



Chionaspis citri, Comst., on the leaves and tender branches. 



Lepidosaphes gloveri, Pack., on the leaves, tender shoots, and fruits. 



Saissetia oleae, Bern., on the young shoots and branches. 



Saissetia hemisphaerica, Targ., on the leaves. 



Coccus viridis, Green, on the leaves and tender twigs. Infestation is sometimes 

 very heavy, two to three hundred larvae and adults occurring on the same leaf. 

 This species is heavily parasitised by two Chalcids, Diversinervus silvestrii, Waterst. 

 sp. n., and Tetrastichus sicarius, Silv. 



I eery a seychellarum, Westw., is a regular pest. 



Pseudococcus citri, Risso, is a minor pest. 



Pseudococcusfilamentosus, CkW. (ms/rt/or. Mask.) is commoner than the preceding 

 species. 



The buds and flowers are intensely attacked by a species of brownish-black aphis. 

 The damage caused to the flowers is great, as a large proportion of them drop. Seed- 

 lings are sometimes infested to such an extent as to cause their growth to be stunted 

 for a time. When such is the case, lateral growths are emitted, to the detnment 

 of the plant. 



Eggs and larvae of a Psyllid, Trioza sp., are found on the lower surface of the 

 leaves at the beginning of summer. The larvae are greenish yellow and reach the 

 adult stage in about a month. Wherever the larvae occur there is a correspondmg 

 swelling of the tissue, resembling a gall, on the upper surface of the leaf. The body 

 of the larva fits exactly into this pseudo-gall, its dorsal part lying flush with the 

 lower surface of the leaf.' Trioza is not a serious local pest, though it occurs sometimes 

 in appreciable numbers. Wlien such is the case, the attacked leaves fall off, though 

 not until the insects have reached the adult stage. 



