NOTES ON BRITISH THYSANOPTERA. 279 
American species seems to have a slightly more constant 
number of spines in the outer half of the fore vein. A number 
of counts of Californian specimens gave 4 fifteen times, 5 four 
times, and 7 once. Specimens from fruit trees in England gave 
4 thirteen times and 5 nine times. Specimens from flowers of 
laurel (England) gave 4 six times, 5 four times, 6 three times, 
T once. ‘l'wo specimens from Bohemia, from the collection of 
Dr. Uzel, gave 4 twice and 5 twice, while specimens from young 
leaves of horse-chestnut in England gave 8 once, 5 twice, 6 five 
times, and 8 once. Apart from this no structural difference 
can be found. The identity is also confirmed by the fact that 
‘Uzel mentions Prunus cerasus as one of the food-plants of 
Physopus inconsequens. It is much to be regretted that the 
mame of a species of such economic importance has to be 
changed, but under the circumstances the name pyri, Daniel, 
1904, will have to give way before the much more unsuitable 
name inconsequens, Uzel, 1895. 
The species has without doubt been in Hurope for many 
years, not usually, however, being injurious. T. Major, in a 
* Treatise on Insects Most Prevalent on Fruit Trees and Garden 
Produce’ (London, 1829), says, on pp. 87-90, on the “ thrip ”’ 
on peach and nectarine, that ‘‘as soon as the least verdure 
appears, both larve and adults are found, the latter becoming 
nearly black.’ They commence feeding on the edges of the 
young leaves as soon as they put forth in the spring, and also 
_ prey on the bloom before it expands. As thrips are so commonly 
‘seen on flowers, he suggests planting rows of Virginia stock and 
Convolvulus minor as trap crops! 
The above account of the habit and time of appearance 
leaves very little doubt that this is the same species, so that 
we have evidence of the species existing in England nearly a 
hundred years ago. 
There are also other reasons for considering that the species 
is a native of Kurope and only an accidental introduction into 
the United States. There are (1) the presence of both sexes in 
Kurope, while females alone are found in the United States. 
In the latter country reproduction is entirely parthenogenetic, 
all the specimens being the progeny of one or a few females 
originally introduced. ‘his might account for the slightly less 
variability found in the American specimens. (2) The rapid 
increase in numbers and spread in range of the Pear Thrip 
in America since its original outbreak indicates an introduction 
into a locality free from natural enemies. It would be interesting 
to discover the controlling influences of the species in Europe. 
(3) The fact that the various fruit trees which are attacked in 
the United States are all introductions from Europe. (4) The 
fact that a nearly related species (7’. primule) is found in Kurope, 
but no other species of the same genus has yet been discovered 
