﻿THE GEANAPvY WEEVIL 23 



30° F., and then removed to a warm temperature, hatched 32 days 

 after deposition. Although 4 days is the minimum period observed 

 by the writers, eggs have been observed to hatch in 5 days after 

 deposition when the temperature for the incubation period ranged 

 from a mean of 68.7° F. (90° F. maximum, 46° F. minimum) 

 and of 82.8° F. (95° F. maximum, 68° F. muiimum). 



Although the data of Table 4 indicate that the length of the incu- 

 bation period is from 4 to 15 da3-s under more normal conditions and 

 may be extended over a period of at least 32 days during colder 

 weather, there are dealers in grain who firmly believe that eggs are 

 capable of passing through a very long period of development, and 

 that they are capable of a suspended development when temperature 

 conditions are iinfavorable to growth, only later to resume normal 

 development upon the return of favorable temperature conditions. 

 It has been found that the female weevils do not begin to mate and 

 lay eggs until the temperature is from 61° to 63° F., and that even at 

 these temperatures eggs are not deposited every day. It is not until 

 the temperature has risen to 66° to 68° F. that mating and oviposition 

 occm- daily. It would appear from observations that eggs are not 

 deposited at temperatures below the minimum at which they can start 

 development. Should the temperature drop to below 50° to 55° F. 

 for a considerable period, there is every reason to believe that egg 

 development is suspended indefinitely and that eggs perish for lack 

 of warmth. No eggs were observed to hatch after the temperature 

 of the grain had reached 95° F. or above. 



THE LARVA 



When the embryo is fully developed, its undulating movements 

 cause a rupture of the thin eggshell, and the young larva emerges to 

 find an abundance of food ready at hand. It immediately begins to 

 feed, burrowing through the tissues of the seed, forming a winding 

 tunnel that increases in size with the growth of the larva. The 

 tunnel is often close to the surface of the seed, and in corn, particu- 

 larly, the progress of the larva is sometimes distinctly visible through 

 the seed coat (fig. 4). 



FOOD OF THE LARVA 



The larva breeds in all the common grains, such as corn (fig. 4), 

 oats, barley (fig. 2), rye, wheat (fig. 3), kafir, l)uckwlieat, millet, and 

 also in chick-peas (fig. 9). It is said to breed in acorns, chestnuts, 

 and sunfiower seeds, although Strachov-Koltchin states that he failed 

 to get them to breed in sunflower seeds. It is unable to breed in loose 

 farinaceous material, such as flour and semolina used in making 

 macaroni, but breeds readily in jnanufactured products of cereals, 

 such as macaroni (fig. 5), noodles, und j)rob;i,bly other similar prod- 

 ucts, and in milled cereals that lia\ c- become })adiy caked fi'om excess 

 moisture. TIh; larva feeds on all parts of the sc.cul, but prefers the 

 soft starchy portion. As it bores und tiiniu^is Ihroiigh the seed it 

 thrusts the borings and frass behind it, so that the jnine it leaves 

 behind is always filled. It has hc^en found that larva; can feed in 

 grsiin with a moistuni content as low as 8 per cent, although feeding 

 undoiibt(!(lly progresses more normally when the moisture content is 

 about \4 to 16 {)er cent. 



