Swarms of locusts blown off the Mediterranean towards the Egyptian capital, Cairo, are not expected to cause major damage to crops.
Locusts can eat their own weight in crops every day
Millions of the insects swept into Cairo and the surrounding Nile Delta region throughout Wednesday.
The infestation of red desert locusts was Egypt's largest since the 1950s.
UN officials believe the locusts, which can consume vast swathes of crops in warm weather, will head to the sea, away from the fertile Nile Valley.
Christian Pantenius, UN food and agriculture co-ordinator in Egypt said the locusts arrived in Egypt after strong southerly winds blew them away from the Mediterranean Sea.
Swarms of pink or red desert locusts, or schistocerca, have swept through Cyprus and Lebanon in recent weeks.
Mr Pantenius said a "medium density swarm of locusts numbering several million, if not a billion", had hit Egypt.
The insects are likely to head towards breeding grounds by the Red Sea, he added, although a programme of pest control was being instigated as a precaution for crops.
Locust swarms have devastated vast swathes of the African interior this year, with millions still present in Mauritania and Niger. Experts say they are beginning to head north towards Algeria and Morocco.