REPOET or THE ENTOMOLOGIST. 343 



INFLUENCE OF "WllATHER. 



It seems to be a pretty generally-settled point among planters, so far 

 as we can ascertaia, that the boll-worm is influenced by the weather in 

 a similar manner to Aletia; that is to say, that they flourish best in wet 

 seasons, and in dry, sunshiny weather do least damage. The testimony 

 on this point is hardly as unanimous as Avith the cotton-worm, but it is 

 sufficiently so to enable us v.ith justice to make the general statement 

 Mr. Trelease says in this connection: 



Like the cotton-caterpillar, tlietoll-wormismoreabundantinwettlianinclryplaces; 

 at least such was mv experience, and it is also said to do better in wet than in dry 

 seasons. This is readily explained by the hostility of ants, which are more abundant 

 in dry than in wet places, and in fair than in rainy seasons. 



Early in June several halt-grown "bud-womie" were collected on Indian corn and 

 transferred to cotton-plants with a view to watching their actions. Care was taken 

 to place them upon plants upon which there were no ants. Seating myself beside 

 them, I awaited developments. At first they evinced no desire to do more than con- 

 ceal themselves beneath the leaves from the glare of the sun. But it was not long 

 ■before a stray ant appeared on the plant, and, finding the larva, proceeded to run 

 round and round it, biting it whenever it could. 



Soon, however, finding that unaided it could do little, the ant left the plant, and, 

 after watching it a short time, I lost sight of it ; but in a few minutes it returued 

 accompanied by several others of the same species. In a little while the worm was 

 BO worried that it fell from the plant, and was soon killed and carried oif by its tor- 

 mentors, which followed it to the ground. 



Several times I saw this repeated, the boll-worm being killed in each case within 

 an hour after the time when they were placed on the cotton. Ants were also seen to 

 kill these larvae upon several occasions, and once or twice when the worms had not 

 been interfered with by me. 



Mr. Lyman, in Department of Agriculture report for 1866, says that 

 many eggs of the boll- worm moth are destroyed by ants. 



The theory of the ants influencing the comparative abundance of 

 worms in wet and dry weather is, as we have said before, an extremely 

 plausible one if its basis be correct. There cannot be the slightest doubt 

 but that ants abound upon dry soil rather tlian upon that which is 

 moist, and in dry, sunshiny weather rather than in rainy weather; nor 

 can there be the slightest doubt but that many species destroy both 

 cotton and boll worms. Then the theory will hold just so far as this 

 destruction goes— just to the extent that the ants kill the worms. The 

 fact that there is a slight difference of opinion as to the influence of the 

 weather can then be easily explained by the comparative abundance of 

 ants in different localities. The theory does not, however, entirely 

 account for facts as observed, but will have to be taken in connection 

 ■with the nectar-gland theory, and also with the facts of the superior 

 nourishing power of a tender and succulent plant, as compared with 

 one dry and dwarfed from drought. 



EEMEDIES. 

 NATURAL KEMEDIES. 



The remarks already made (see page 305), concerning the efficacy of 

 insectivorous birds aud of predaceous insects will apply equally well 

 here. Strange to say, but one parasite upon HeUotlm has been found. 

 This was bred from a chrj^salis received September 15, 1879, and proved 

 to be TacJdna aletiae. (See page 302.) 



Professor Edey, in a foot-note in his fourth Missouri report, mentions 

 Heliothis armlgera as being among the species from which he had bred 

 Tacliina anonyma. (For the habits of the Tachina flies see page 302.) 



