Properi;' of »'"° I'rv °d si 
 
 Circular no SO. 
 
 
 United States Departmenl of \gr 
 
 BUREAU OF KNTOMOLOGY, 
 
 L. n M'>W*KH Kntomologto und Our! 
 
 III ^^ 111 I I I'lM \\l I \ II . 
 
 
 
 
 D. Hopkins, 
 
 i^t urn 
 
 The Bureau of Entomology has been conducting systematic ana eco- 
 nomic investigations "f the weevils infesting the bark of the trunk and 
 terminal shoots of conifers in the United States, the results of which will be 
 published in the regular technical and popular bulletins; bul Bince 
 
 Fid l Her I'lL-im- Datura I Hue at 
 
 i iult KbowitlR inituriil mil ' 
 
 can not be issued in time t" be of Bervice this Beason, this circular 
 has been prepared to give the information Which is of immediate prac- 
 tical importance in regard to one of the mosl destructive of these weevils. 
 
 I Hi: l\-i:< T \M> ITS H IBITS. 
 
 The white-pine weevil is a Bomewhat elongate, brownish Bnout beetle, 
 l to 5 nun. in length, having the thorax and elytra marked with irr» u'- 
 ular spot- of brown and white - 1, </). The winter is p 
 
 in the adult si ridently in the ground. The beetles come out of 
 
 their winter quarters and By early in May. and after feeding for a few 
 days on the hark of the living white-pine terminal shouts deposit their 
 
 ■ \ Peck; Order Coleoptera, Family Carcnlion 
 
eggs in punctures in the bark of the shoot of the previous year's growth, 
 placing one or two eggs in a pit or cavity in the inner bark made by 
 
 the beak of the mother beetle. In 
 from .six to ten days the eggs begin 
 to hatch into small white grubs 
 (larva), which at first arc usually 
 found in large numbers feeding 
 upon the inner hark and cambium 
 (see fig. 2). They usually work 
 downward and sometimes extend 
 their work into the hark of the 
 2-year-old stem and base of the 
 branches. By the time the larva: 
 have completed their development 
 (fig. 1, h) they are greatly reduced 
 in numbers by natural enemies and 
 other causes. The survivors bur- 
 row into the wood or pith of the 
 terminal and excavate individual 
 transformation cells, which they 
 line and cover with excelsior-like 
 borings. In these cells they trans- 
 form to pupa 1 (see fig. 1, c) and 
 adults, and during July and August 
 of the same year, when the adults 
 are fully matured, they bore their 
 way out and seek suitable places 
 in which to pass the winter. 
 
 LONG LI1T. (iK THE ADULT. 
 
 From recorded observations on 
 some species of Pissodes or bark 
 weevils by investigators in Europe, 
 and on representatives of other 
 allied forms in Europe and in this 
 country, it appears that an indi- 
 vidual adult may live two or three 
 years and will deposit eggs each 
 year. 
 
 SEASONAL BISTORY. 
 
 Km 
 
 -White pine weevil: Newly hatched larvi 
 
 The beetles are active from about 
 .n work in riBorous terminal shoot of white t ], ( , ]s( fc the loth of Mavor later, 
 pine (Author's illustration.) . 
 
 depending on local conditions and 
 
 weather. Eggs are evidently deposited during the principal activity of 
 the adults, possibly during the greater part of the month of May. The 
 
• I of development of the larvae varies greatly. Those more fortu« 
 
 n.it. • in Becuring a continuous I i Bupply ma) become fully developed 
 
 before 8 e of the lesa fortunate ones in the same terminal are one 
 
 fourth as large, although the i •.- from which both came maj have been 
 deposited at aboul the Bame time. There ie also .1 wide range in the 
 period of transformation to the pupa and adults and again in the emer- 
 gence of the latter. Thus, it' the Brsl 1 deposited aboul the v 'h 
 ofMayal (Kilford, Pa., latitude ll 20\ altitude 500 to 1,000 feet, the 
 will begin ti> hatch aboul the 1 Itli of May, the Brsl larva- will 
 be full grown aboul July s . the first transformations to the pupa will 
 take place about the 15th of July, the first adults will begin t" emerge 
 about July 25, and adults will continue to come out until tin- first part 
 of September. Practically all will be out by September I 5. The prin- 
 cipal period of emergence, however, is from about the 25th of July t<> 
 the middle of August. 
 
 KINDS OF TREES \ IT iCKED. 
 
 The white pine is the tree normally attacked, but the weevil is occa- 
 sionally found in the terminals or topmost branches of the native and 
 cultivated spruces, the jack pine, and very rarely in the pitch pine or 
 other eastern piti<~ . The attack is confined to the small to large Bap- 
 ling and pole stages in the development of the tri 
 
 DISTRIBUTION. 
 
 Our records indicate thai this weevil follows the natural range of the 
 white pine from southwestern North Carolina into New Brunswick and 
 Canada and westward int . > Wisconsin. 
 
 i:\ [DEN< 1: OF ATTACK. 
 
 The Brat evidence of attack on the living terminals is the exudation 
 of fresh, clear, and shining drops of resin. Upon closer examination 
 
 fresh pinhole-like puncture-, are found in the hark (t § ml at the 
 
 same time the inconspicuous beetles maj be found on the terminal ; but 
 upon the approach of the observer the beetles will often let go their 
 
 foothold and fall to the ground, where they will feign death. In a few 
 day- after the first attack the injured terminals will have the resin 
 more or less abundanl and conepicuous over the greater part of the sur- 
 face. The first evidence that the terminals are infested with larva- is 
 the stunted, unhealthy appearance of the young growth at the tip. 
 which will gradually die. the m turning yellowish and later 
 
 brownish. 
 
 The time of development of the broods to adults will he indicated by 
 the lirst appearance of dead tips. 
 
 Did work of the weevil is evidenced by the 1 of old dead ter- 
 
Pig. 8.— Work of white-pine weevil, showing character oi injury, chip cocoons, and pupal cells: 
 a, Vigorous terminal shoot, Bhowing condition of nev growth at time pupa' are transforming 
 to adults; b. 8-year-old top, showing how larvae have migrated from terminal to the 2 and 3 
 year old Internodea ; e, chip cocoon ami pupal cell, natural size. (Original.) 
 
minala in the forks 
 < . f the young In 
 (fig. I), and ill" re 
 suits of their work 
 
 will lie evident ill the 
 
 deformed ^ ro \\ t li . 
 
 f <>rk > . and 
 
 broad, low crow n.» ol 
 both young ami old 
 trees ( t i lx . 5). 
 
 CHARACTER "i THE 
 DAMAGE. 
 
 'I'lir damage and 
 loss, as affecting the 
 commercial tree, con- 
 i not only in the 
 death of the terminal 
 •dioots, hut in Mlh>e- 
 
 quent abnormal de- 
 velopment of t li e 
 
 trees BO injured. The 
 
 dying of the leading 
 shoot throws the next 
 year's growth into the 
 Upper lateral -hoot-. 
 which results in a 
 forked and many- 
 branched top. Each 
 branch produces a 
 
 vigorous terminal, 
 and all compete for 
 leadership in forming 
 the crown. In BUC- 
 Ceeding years the 
 more vigorous termi- 
 nals of the topmost 
 branches are at- 
 tacked and killed. 
 causing morebranch- 
 and thus effec- 
 tually preventing the 
 development of the 
 normal straight trunk 
 and symmetrical crown necessary to a tree ot commercial value. 
 
 initial 
 
I 
 
 EXTENT OP DAMAGE. 
 The extent of damage, as affecting natural reproduction, planta- 
 tions, and tim- 
 ber of commer- 
 cial size in the 
 forest, is difficult 
 to estimate ; but 
 it is an impor- 
 tant item to be 
 charged to the 
 losses in com- 
 mercial growth 
 of white pine and 
 is therefore a for- 
 estry problem 
 which must de- 
 mand special at- 
 tention in the 
 future manage- 
 ment of wood- 
 lots and forests, 
 wherever the tree 
 predominates. 
 
 FAVORABLE AND 
 
 X F A V OKABLE 
 CONDITIONS FOR 
 
 DESTRUCTIVE 
 WORK BY THE 
 WEEVIL. 
 
 The most fa- 
 vorable condi- 
 tion for serious 
 injury by this 
 weevil consists 
 in a scattering or 
 open pure stand 
 of young white 
 pine where the 
 growth is healthy 
 and rapid, such 
 as is found in 
 open planta- 
 tions, in aban- 
 
 ... r „ 7 , , , . doned fields, and 
 
 Fig. 5.— Work of white-pme weevil, showing result of killed terminal 
 
 shoot in 8-year-old top of large sapling. (Original.) around the bor- 
 
.,, dense stands wherever the Boil and other conditions are moal 
 favorable for rapid growth. 
 
 The unfavorable conditions for injury are bIom growth, dense pure 
 stands, and mixed Btande of pine and hardwood. 
 
 Under the former conditions the thriftj . vigorous terminals are espe- 
 cially fuvored as breeding placee for the weevil ; and where these are 
 Killed, the vital energ} of the tree i thrown into the lateral branches. 
 O pen stands, then fore, favor the developmenl ol large branches and a 
 spreading crown, while under conditions unfavorable to weevil injury 
 the terminals are Bmaller and, even if they are killed, the close Btand or 
 lateral Bhade will tend to produce an upward or vertical growth of the 
 topmost branches, the stronger one taking the lead and Boon repairing 
 
 the damage. 
 
 \ vn i; \i. ENEMIES. 
 
 Numerous parasitic and predatorj insect energies attack the develop- 
 ing broods in the terminals. Woodpeckers, ed on the matured 
 
 terminals! II. with win erendallow- 
 
 larva>, pupa 1 , and adults. Some of the larva' apparently die from 
 3e , and when large numbers of them are crowded together the 
 larger ones appear to feed on the -mailer ones, bo thai on the average 
 not more than from 3 to 5 per cenl of the hatched larvae ever reach 
 maturity and emerge from the infested terminals. However, each 
 female is capable of depositing more than one hundn each year 
 
 for several years; thus the depredations arc continuous. During Borne 
 years the damage will be Blight, while in other years it will be very 
 severe, the amount of injury depending on the number of adults that 
 survive and the conditions presented for their attack and development. 
 
 mi: rin >i» i >k i < iNi'iv'i 'i i. 
 
 It will be -ecu that in the successful control of this pest, as in the 
 control of forest insects in general, much depend.- on Bpe< ial features in 
 
UNIVERSITY OF FLORIDA 
 
 8 3 1262 09216 4630 
 
 the general methods of forest management which will hring ahout 
 unfavorable conditions for injury and thus prevent loss. 
 
 It will also be seen how important it is to know the principal facts 
 in regard to the life history and habits of the insect, in order to secure 
 the best results from methods of management and of direct control. 
 
 Heretofore this species lias been confused with another species with 
 very different habits, and some of the published data and recommen- 
 dations based on such confusions are of no value. 
 
 The white-pine weevil rarely, if ever, passes the winter in the termi- 
 nals. The present evidence indicates that it never breeds in the thick 
 hark on the trunks and stumps of the white pine or other pines; thus 
 it can not he trapped in the trunks of felled and girdled pine. 
 
 DESTRUCTION OF THE BROODS. 
 
 The only practical method of destroying the weevil appears to be the 
 treatment of the infested terminals, and to secure the best results spe- 
 cial attention must be given to certain important details. 
 
 If the infested terminals are cut or broken during June and July and 
 burned, the broods of the weevil will he effectually destroyed, but vast 
 numbers of natural enemies will also be destroyed. A better method 
 is to collect the terminals during the first half of July before the beetles 
 begin to emerge and to place them in tight barrels securely covered 
 with wire Hy-screen netting on one or both ends (see fig. 6). The bar- 
 rels should be left in the groves, so that the parasites and other 
 enemies may escape, while the beetles perish. After the 1st of October 
 the weevils will all be dead, and the netting may then be removed, 
 although the barrels with their contents should be left until the follow- 
 ing June to allow the escape of the later developing and larger parasites. 
 The barrel should not he placed in a position to collect rain. It is 
 necessary, however, if this method be adopted, that it he repeated two 
 or three years in succession in the same locality, in order to catch the 
 successive hroods from the old parent beetles that live over from pre- 
 ceding years. 
 
 NOTE. 
 
 The statements and recommendations in this circular are based on recent 
 observations and investigations by the author and by Field Assistant W. F. Fiske, 
 and serve as a partial revision of what has hitherto been published. 
 
 Approved : 
 
 James Wilson, 
 
 Seen tiir;/ of Agriculture. 
 
 Washington, 1). C, May 21, 1907. 
 
 O