The Delhi government on Thursday warned of a possible locust invasion and asked authorities to spray insecticides and pesticides on crops, vegetation, gardens and orchards while several states in western and central India struggled to contain the worst infestation in nearly three decades. Overnight operations were carried out by authorities in Uttar Pradesh's Jhansi district while those in Madhya Pradesh used police sirens and urged farmers to beat utensils as locust swarms which first attacked Rajasthan and Gujarat, have now spread deeper into many states including Maharashtra, Haryana and Punjab.