Jheronimus Bosch abroad

In 1521, patrician Marcantonio Michiel recorded what he saw at the Palace of Cardinal Grimani in Venice: “A canvas of the hell ... by Jheronimus Bosch, a canvas with dreams of the same [maker], and a canvas of the whale swallowing Jonah”. Michiel's report does raise questions, for the pictures can hardly be compared with the paintings we still have today and he talks about canvases, while we now only know panel paintings by Bosch, but at the same time it does say something about Bosch's reputation in Venice. Some people consider it an indication for Bosch's stay in Italy.
A second indication is found in Bosch's painting of the Crucifixion of St Julia. Two female martyrs are known who are depicted on the cross: Wilgefortis and Julia. Wilgefortis can usually be recognised on her beard, but it is not shown on the triptych. The other one, Julia, is worshipped in Italy, particularly near Brescia. The two side panels used to show two donors in Italian clothing with Italian instruments.
So both indications may very well point in the direction of Italian patrons, but that doesn't necessarily mean Bosch must have been in Italy. In particular Italian merchants had close contacts with the Netherlands; economic and cultural relations were very intensive.

The reason that some people think Bosch spent some time in Spain, is based on the popularity of his works in Spain. Without exception, his works were owned by families in high places. Already before 1508, the De Haro family possessed a triptych in the style of Bosch titled “The patience of Job”. Beatrix de Haro was married to the nobleman and art connoisseur Don Felipe de Guevara, who was also the first to write a comment to the work by Bosch. Together they possessed as much as six paintings by Bosch around 1560. As early as in 1504, Queen Isabella of Castile also owned at least one, but maybe even five paintings by Bosch.
Although there is no doubt whatsoever about his enormous popularity among Spaniards, that still does not prove that Bosch stayed there. There were many Spaniards in the Netherlands and the works could also have been bought here and then brought to Spain.

Two periods can be identified when Bosch stayed elsewhere and could have been travelling. In both cases this refers to a period in which his name is not found in the archives.
The first period was from 1474 to 1481. In advance, Jheronimus and his father borrowed a sum of money. Maybe he needed money to pay for his travels. 
The second period was from 1498 to 1504. In 1498, Bosch issued a power of attorney so someone else could perform legal acts in his name. In 1499, when it was Jheronimus's turn to invite his fellow brethren, the meal was held at someone else's place.

Though there are indications that Bosch was absent during certain periods and though there was a South-European clientele, there is no proof for Jheronimus Bosch's stay abroad. Moreover, it is remarkable that no clear change can be perceived in Bosch's work after such a presumed stay elsewhere. Neither can it be demonstrated that artists in foreign countries felt inspired by this remarkable painter.