THE MONTHLY BULLETIN. 311 



Legal measures designed lo prevent the introduction and establishment of the 

 orange maggot have been taken by both the federal and slate governments. The 

 importation of all its hosts from Mexico is prohibited in United States Notice of 

 Quarantine No. .">. The immediate destruction of the hosts of the Mexican orange 

 maggot wlirn brought into California is authorized by sections 5 of the State Quar- 

 antine Law. 



THE GIPSY MOTH AND THE BROWNTAIL MOTH. 



By Harry S. Smith. 



Two arboreal pests in which Californians are interested are the moths mentioned 

 above. The State Commission of Horticulture has considered it unnecessary to quar- 

 antine New England against these pests, for the reason that they are perhaps the 

 most easily detected of any insect enemies of trees which are likely to be introduced 

 into this state. Also the Federal Horticultural Board sends to the horticultural 

 quarantine officer an advance notice covering each and every shipment coming from 

 the infested area into California, dealing in detail with each individual shipment 

 covering the certificate, number, quantity, consignee, destination, date shipped, route 

 and product, and includes plants, holiday decorations. Christmas trees, lumber and 

 stone. Our quarantine guardians have acquainted themselves with the nature of 

 these insects and have been instructed to keep close watch for them in any shipments 

 from infested regions as well as from Europe. That they are continually on the 

 watch is evidenced by the fact that both these pests have frequently been taken in 

 this state on shipments of nursery stock. 



The gipsy moth was accidentally introduced into New England in about the year 

 1809 by a Frenchman who was interested in silk culture and who was trying to 

 develop a resistant strain of the silkworm in crossing it with the gypsy moth. Some 

 of the insc.is which he had in captivity were allowed to escape and from this begin- 

 ning the gipsy moth has gradually spread until it is one of the most important insect 

 posts in the United States. For a number of years it has cost the federal govern- 

 ment and the states infested a sum amounting to nearly one million dollars annually. 

 and yet the insect continues to invade new territory in the northeastern states. 



The female moth has about 2i inches of wing-spread and is of a creamy white 

 color with delicate brown markings. The abdomen is covered with buff hairs. The 

 male is much darker in color and about two-thirds the size of the female. The eggs 

 are laid on the trunks of trees and on rocks and fences, and are deposited in clusters 



of from 300 to 0(10. The egg clusters ar ivered by the hair from the body of the 



female moth, giving them the appearam f a small oval piece of chamois skin. The 



young larva: are covered with long hairs and are so light that they are easily blown 

 about by the wind. The full-grown larva reaches a length of nearly three inches and 

 is prettily colored. The pupa is practically naked and of a dark brown color, and is 

 found in protected places, on the trunks of trees, on rocks, fence rails, etc. 



The gipsy moth passes the winter in the egg stage, hatching usually in the month 

 Of May. The larvae are full-fed about the lirst of duly and the moths emerge and 

 the eggs are laid during this mouth. The caterpillars strip the trees and shrubs of 

 their leaves, frequently completely defoliating the entire woodlands. They feed upon 

 almost all of our deciduous trees, oak being the preferred host, and in the later stages 

 will also feed upon the conifers. 



The insect is distributed to a considerable extent on nursery stock and also on 

 vehicles, lumber, quarry and other products. The caterpillars are also scattered by 

 the wind as mentioned above, and by dropping into trolley cars, automobiles, etc. 

 The females are unable to fly, so that no dispersion takes place by this means. 



The control measures consist of painting the egg masses with creosote, which pre- 

 vents them from hatching. The trees are also banded with tree tanglefoot, which 

 prevents the young caterpillars from crawling up the I tees. The most effective 

 method of destroying the pest is a thorough spraying with arsenate of lead at the 

 rate of five pounds of paste to fifty gallons of water. 



The Bureau of Entomology has for several years carried on an importation of the 

 most effective parasites of this insect from Europe. Many of these are now estab- 

 lished in New England and an- giving a g 1 account of themselves. It is probable 



that in the woodland areas control will resolve itself into the use of natural enemies 

 together with the cutting out of the favored host trees. The Federal Horticultural 



