PRICKLY PEARS NOW WILD IN INDIA. 
819 
Calcutta up the Ganges valley and over the Punjab plain to Ludhiana — 
rather more than 800 miles away. Its progress through Bengal is 
unrecorded ; but the Opuntia had become a pest in the Punjab, and its 
destruction made such a difference to the face of the country that 
writers promptly noticed and recorded what was happening. 
Opuntia monacaniha, thanks to the cochineal insect, which is still 
with us, is now a comparatively scarce plant. Its survival in Assam in 
greater quantity than elsewhere is due to the isolation, by reason of the 
submersion of the country in the rains, of sites suitable for it. The 
Cactus being used by man for fences, has been carried over the 
barriers, but not the cochineal. 
The abundance of the Cactus in India before its enemy, the cochineal 
insect, was introduced seems to be proof that the Portuguese did not 
introduce the latter into India : I do not know any reason for stating, 
as has been done, that they probably did so. 
Opuntia Dillenii, unchecked by the cochineal insect, has continued 
to spread in Southern India and is now the commonest species there. 
It occurs about Calcutta ; and before 1840 it had been taken to Agra, 
where it grows still. 
Opuntia elatior ran wild after 1800 from Calcutta and spread 
through the north of India. Its great prevalence about Patna and 
Delhi suggests that it was early taken to those two places. Prom 
Delhi it was taken to the Deccan, where its spread has been most rapid. 
It is now invading the Central Provinces from the west, and has reached 
Nagpur. It is in Western India sometimes attacked by the cocoid 
Diaspis cacti ; but the attack is mild. 
Opuntia cochinelifera has never got a firm hold in the country, but 
has been taken since 1800 to various places including Burma. 
The failure of the spineless Opuntia cochinelifera and ^he one-spined 
Opuntia monacantha to take firm hold of the country, though largely 
due to the avidity with which the wild cochineal attacks them, is also 
due to the inferior fence that they make. The rapid dispersal of 
Opuntia elatior and Opuntia Dillenii through the country has been 
undoubtedly due to their use in making fences. A practice of the 
middle part of the last century of using them round cantonments, 
and the fine fence, — the ‘ Salt-wall,^ — made over miles of country along 
the Rajputana border to prevent smuggling, undoubtedly afforded the 
plants" many new starting points for fresh encroachments : even now 
0 . elatior forms a splendid jail fence at Dharwar. Thus have they 
