GENER.\I. 1 219 



Lyda which have pupal eyes. P'rom this it follows that these parasites have 

 a single generation per year, and that they only attack the Lyda larvae still 

 living on the tree. 



Control. — Judging from the life histor}^ of Lyda, it seems that expens- 

 ive control measures are not justifiable. The larvae almost always eat 

 the needles of the previous year and very rarely those of the actual year. 

 Consequently the developing buds are not attacked by them. The growth 

 of the trees suffers from the influence of the larva, but not very much. It is 

 consequently advisable to abstain from any control measures against this 

 enemy. The writer recommends that greater importance should be attached 

 to the other enemies of the spruce which accompany Lyda, such as : Pis- 

 sodes hereyniae, P. scabricollis, Ips typographus, Pityogenes chalcographus, 

 etc. The method of pasturing pigs in the forest in order to destroy the larvae 

 of Lyda is hardly practicable. 



946 - White Grubs {Lachnosterna spp.) in Wisconsin, United States of Ame- 

 rica. — Santjers J. G. and FR-\cker S. B. \n Jouinal of Economic Entomoloc^y, Vol. 9, 

 No. 2, pp. 253-261, Fig. 3. Concord, N. H., 1916. 



The results are here set out of a .series of researches and experiments 

 on white grubs {Lachnosterna spp.) undertaken at Madison, Wisconsin, 

 in 1914-1915. 



In order to capture the insects, light traps were employed (Coleman 

 gasoline lamps of 300 to 400 candle power) placed near the receptacles con- 

 taining water to which paraffin had been added, into which the insects, at- 

 tracted by the light, fall. In Wisconsin there are five Stations (Lancaster, 

 Dodgeville, Baraboo, Madison and Ripon) each provided with eight lamps. 



From May to June 1915 there were captured i 036 400 specimens of 

 Lachnosterna belonging to the following species : L. fusca, L. rugosa, L. 

 grandis, L. dubia, L. hirticida, L. gibbosa, L. ilicis, L. balia, L. tristis, L. ni- 

 tida, L. implicita, L. marginalis, L. vehemens, L. nova, L. prunina, L. inversa 

 and L. villi frons, L. fusca certainly the most widely distributed species ; 

 L. rugosa was not reported at Lancaster but was very common in the other 

 Stations lying further north. 



In the early morning, in the evening, and generally when the days are 

 cold, the larvae are rarely active and do not feed. On the other hand they 

 are very active and voracious during the hottest hours of the day. Migra- 

 tions in a vertical direction commenced by the insects under the influence 

 of temperature variations are never observed in the soil. The larvae ge- 

 nerally remain at the same level near the surface of the soil from 

 which they only shift to go in search of their food. The latter consists of 

 root or parts of roots. If the larvae are brought into contact with freshly 

 germinated young plants they attack and destroy the radicle without 

 touching the stem. They refuse bran or sweetened dough. 



A number of larvae were left for five and a half months in a vessel con- 

 taining only soil, and no food was given them. At the end of the period of 

 experiment, two larvae were still alive and active ; they had fed only on the 

 small amount of vegetable detritus contained in the soil. In view of this 



