The Garden Magazine, July, 1924 
355 
phenomenon known as alternation of generations. That 
is, succeeding generations are unlike, though grandparents 
and grandchildren are identical. There is an equally strik¬ 
ing difference between the galls inhabited by the two differ¬ 
ent generations. It is possible that practical methods of 
controlling these injurious species could be developed if the 
complete life-history were known. Unfortunately, we are not 
certain as to the gall produced by the alternate generations of 
these gall wasps and consequently can suggest nothing particularly 
effective in the way of control. There is a possibility that spray¬ 
ing trees badly infested by these galls with molasses and water, 
using six pounds of molasses to fifty gallons of water, would trap 
many of the insects as they attempt to issue from the galls, 
provided the application could be timed so as to anticipate the 
period of greatest emergence. 
There is a somewhat beautiful twig gall on the Bald Cypress 
of the South. It is oval, about half an inch long and usually 
brownish; a greatly swollen portion of a branch bearing rudi¬ 
mentary leaves and containing yellowish or orange colored 
maggots destined to develop into fragile gall midges, insects 
quite distinct from gall wasps. 
The Soft Maple and the Cottonwood are frequently more or 
less disfigured by the galls produced bv tiny 
mites. Those upon the Soft Maple leaves are 
about one eighth of an inch in diameter, greenish 
at first, turning reddish and eventually black. 
They may be so extremely abundant as to 
seriously deform the foliage, though we have yet 
to note a case where the vigor of a tree was 
greatly impaired in consequence. 
A related mite attacks the blos¬ 
soms of Poplar and Cottonwood 
and transforms them into an ir¬ 
regular, unsightly mass of tissue 
which remains upon the tree over 
GALLS OF THE WOOL SOWER 
The creamy-white, wooly matter with its spotting of crimson is in 
itself a beautiful object though a sad affliction for its host the Oak 
SOFT MAPLE LEAF 
Showing the numerous pouch galls 
of a blister mite. Early spring 
spraying with lime sulphur or a 
miscible oil is a specific for this 
trouble 
winter and is undesirable from 
an esthetic standpoint. 
Winter or early spring spray¬ 
ing with a lime sulphur wash or 
a miscible oil appears to be a 
specific for infestation by both 
of these gall mites. 
IT SHOULD not be assumed 
1 from the foregoing that gall 
insects limit theirattack to trees. 
There are more than fifteen 
hundred different galls occurring 
upon many kinds of plants, the 
abnormal growths developing 
upon the roots, the stems, the 
leaves, in leaf or flower buds, or 
even in the fruit, much depend¬ 
ing upon the plant and the insect 
attacking it. The Oaks are fa¬ 
vorites with the gall wasps; the Hickories with certain gall¬ 
making aphids related to the well known grape phylloxera; and 
the Asters, the Goldenrods, and Willows afford food and shelter 
to long series of gall midges. 
It is interesting in this connection to note that many of the 
peculiar blister-like developments upon the leaves of Asters, 
Goldenrod, and some related plants are the work of gall midges, 
though in earlier years they were supposed to be produced by 
certain fungi. There is also a beautiful flower-like gall upon: 
the Bald Cypress of the South, likewise caused by a gall midge,, 
though it was at one time supposed to be of fungus origin. 
ATROPHIED 
GOLDENROD 
Attacked by insects 
while the tissues are 
still in the bud, the 
arrested tip of the 
Goldenrod takes this peculiar 
form known as a rosette gall 
O 
