154 
sparrows do more harm than good. The style of the book is attractive, 
but the statements, many of them, will not bear the test of scientific in- 
quiry. 
OCCASIONAL DEVELOPMENT OF WINGS IN NORMALLY APTEROUS 
HEMIPTERA. 
Mr. J. W. Douglas, in a review of Mr. F. B. Pascoe’s recent work on 
the Darwinian theory of the origin of species (The Entomologists’ Monthly — 
Magazine, April, 1891, p. 109), calls attention to the statement that ‘‘Some 
of our Hemiptera, Nabis, Pithanus, Pyrrhocoris, etc., ordinarily wingless, 
are sometimes found in hot summers to have well-developed wings.” 
As Mr. Douglas remarks, all these species normally have rudiments of 
elytra, but there are other species quite apterous in which at times 
macropterous individuals appear, in which case the respective forms are. 
so divergent as to be considered distinct. But he does not believe that 
such dimorphism occurs only in hot summers, and mentions having ob- 
served it in cold seasons also, when there was nothing exceptional in 
the weather to favor such development. He believes that at present 
no satisfactory explanation can be given. May it not be that the devel- 
opment of wings is dependent somewhat on the food supply of the insects, 
and they are produced to enable a more extended migration, rendered 
necessary by a diminution of the food supply or the overdevelopment 
of the species? The abnormal appearance, locally, of winged specimens 
of a wingless species can not be satisfactorily explained by the theory 
of a reversion to a winged ancestral type, since this would account for 
isolated cases, but would hardly explain the general appearance of 
winged individuals. secre 
AN ARGUMENT AGAINST SPRAYING FOR SCALE-INSECTS. 
In the California Fruit Grower of January 31 we notice a com. 
munication from Mr. F. Righter, who states that at the last meeting of 
the Campbell Horticultural Society the subject of the best materials to 
destroy the brown apricot scale was discussed, and that it was generally 
concluded that it was better not to spray at all, as those orchards which 
had not been sprayed were found upon examination to be freer from 
scale than those which had been sprayed annually. Orchards which 
had not been sprayed and which were at one time badly infested with 
this scale were said to be now entirely free from the pest. If these facts 
are correct the deduction is also correct, but itis evident that some 
important natural enemy of this bark louse has been at work. It was 
the supposition of the members of the society that the Vedalia had 
killed off the scale, but this is entirely contrary to the experience of our 
agents and correspondents. It seems certain that Vedalia will prey 
upon nothing in this country but Icerya purchast. The item in its 
present shape, however, is calculated to do considerable harm, and no 
horticulturist should neglect spraying in consequence of this exceptional 
experience. 
