ENTOMOLOGY 151 



importation from Europe, it is largely kept in check by parasites and 

 only occasionally becomes a serious pest. 



Cabbage Maggot. This is one of the most serious insects that 

 growers of this vegetable have to contend with. Young plants, soon 

 after being set out in the spring, are often found to have their roots 

 infested with these maggots, their presence being indicated by the 

 dying of the plants. They are white, footless larvaB, the offspring of 

 slender two-winged flies, smaller than the ordinary house fly; the 

 eggs are laid on the stems of the plants close to or just beneath the 

 surface of the ground ; when hatched, the maggots burrow down into 

 the roots, where they tear the tissue with the hooks which take the 

 place of their jaws, and live upon the sap; the breaking up of the 

 cells of the plant causes a rot to set in and the entire destruction of 

 the root soon follows. When full grown the maggots form their 

 reddish brown puparia in the soil near by, and from these a second 

 brood of flies soon emerges. Working under ground as they do, it is 

 a difficult matter to apply any effective remedy; the only one that 

 has proved useful is a decoction of pyrethrum insect powder 

 (quarter of a pound to a gallon of water) or white hellebore of the 

 same strength. The earth is drawn away from the root of an af- 

 fected plant and half a tea-cupful is poured in ; the soil is then re- 

 placed and hilled up around the stem. 



Preventive measures are less troublesome and usually more 

 effective. One of the best is the screening of newly set-out cabbages 

 and cauliflowers with cheese-cloth. Light frames of slats are made 8 

 feet long, 2 wide and 2 high ; over these is tacked cheese-cloth which 

 should reach to the ground on all sides, and be prevented from blow- 

 ing about by heaping a little earth on all edges. These frames cost 

 very little and can be readily moved when required and stowed 

 away for future use ; they should be put on as soon as the plants are 

 set out and left till they are well-grown. The frames not only pre- 

 vent the flies from laying their eggs on the plants, but also keep off 

 the other insects which are liable to attack them. 



Tarred paper disks, three inches in diameter, with a slit from 

 one side to the middle, are used to place around the stems of plants 

 when they are set out, and prevent the flies from laying their eggs 

 upon them. These are somewhat troublesome to make and put on 

 and are not nearly so effective as the cheese-cloth screens. 



Cabbage Aphis. From mid-summer until fall, cabbages are 

 subject to attack by plant lice. Of course the lice are present earlier 

 in the season but in such small numbers that they escape detection. 

 Both winged and wingless forms occur, all of them being covered 

 with a coat of fine waxy powder, very much like the bloom on the 

 leaves of the cabbage on which they rest. This waxy bloom, no 

 doubt serves as a protection by helping to conceal the insect, but 

 when we come to spray we find that it helps very effectually to repel 

 the liquid. Lying, as they do, in closely packed colonies, which 

 sometimes cover almost the entire underside of a leaf, one would 

 expect to kill them with ease. One finds, however, on trying to do 

 eo, that most spray mixtures slide from them like water from a 



