APPLE PESTS 



529 



Professor Slingerland, of Cornell Uni- 

 versity, has pointed out that in the ex- 

 perience of some of his correspondents, it 

 Is very difficult to kill this green fruit 

 worm after the apples are large enough 

 to furnish food. It is probable that an 

 early spraying would be effective and we 

 recommend that four pounds of arsenate 

 lead be aide! to every oil gallons of lime- 

 sulphur or the tobacco extract applied 

 just before the fruit buds open, or in 

 water at the same time or a little earlier 

 if there is no other pest requiring treat- 

 ment. 



R. A. COOLEY, 

 Montana Circular No. IT. 



Gypsy Moth 



Porthetria dispar Linn. 



By H. F. Wilson 



Like many other of our most serious 

 pests this insect was imported from 

 Europe and has been the cause of consid- 

 erable trouble in this country. We do 

 not as yet have this pest in the North- 

 west, but everyone is warned to be on 

 the lookout for it. 



The eggs are deposited in masses meas- 

 uring three-fourths by one-half inches 

 and containing approximately 500 eggs. 

 At first these egg masses are yellowish in 

 appearance but during the winter, ex- 

 posure to the weather causes them to be- 

 come a dingy white. The individual eggs 

 are about the size of a pinhead, and when 

 first deposited are salmon colored, turning 

 dark in the course of a few weeks. 



These eggs hatch in the spring and each 

 egg mass produces a mass of young dark 

 caterpillars, which become full grown by 

 midsummer. The caterpillars are decid- 

 edly hairy and as they grow older as- 

 sume a varied coloring along the back. 

 Starting from the head, which appears 

 mostly yellow, may be found a double 

 row of five pairs of blue spots; these be- 

 come very distinct on the larvae as they 

 reach maturity and as the larvae are en- 

 tirely distinct from any others which we 

 have in the Northwest, they should be 

 easily recognized if one meets with them. 



When full grown, which is in midsum- 

 mer, the caterpillar spins a few strands 

 of silk for support and changes to a chry- 



salis, which is the pupal stage. In this 

 stage they are dark reddish in color and 

 thinly sprinkled with light reddish hairs. 

 They remain in this stage for about two 

 weeks and then change to the adult in- 

 sect. The female moth is white with nu- 

 merous black markings, is quite robust 

 and moves about very sluggishly. 



The male is brownish yellow with some- 

 times a greenish tinge. They fly about 

 during the day and after mating with the 

 females live but a very short time. The 

 males measure about one and one-half 

 inches from tip to tip of wing. The fe- 

 males measure about two inches but do 

 not fly and therefore do not spread as 

 rapidly as they might. After copulation 

 takes place the females deposit their eggs 

 and die. 



This pest is probably mostly distributed 

 by egg masses on nursery stock, but as 

 the larvae have a habit of spinning webs 

 and dropping from trees they are often- 

 times carried on automobiles and other 

 vehicles for long distances. 



The gypsy moth caterpillar will attack 

 all fruit, shade and woodland trees. Apple 

 trees seem to be preferred above all 

 others. 



There are many natural enemies of 

 the gypsy moth and in Europe these are 

 suflicient to keep it under control. 



In the United States it will be neces- 

 sary to wage combat until such natural 

 enemies as are being imported can in- 

 crease to numbers corresponding to those 

 of the gypsy moth. 



Remedies 



The most effective time to catch this 

 insect is in the egg mass. These wher- 

 ever accessible, can be killed by soaking 

 them in creosote. When the caterpillars 

 are quite small they can be poisoned 

 with arsenate of lead at the rate of 10 

 pounds to 100 gallons of water. This can 

 be applied with any of the common force 

 pumps. 



Natural Enemies 



(The numerous parasites which the en- 

 tomologists of the Department of Agricul- 

 ture have imported, it is stated, are be- 

 ginning to control this pest. — Ed.) 



