26 



THE AGRICULTURAL NEWS. 



January 16, 1904. 



INSECT NOTES. 



Fig. 2. Ey 



The Cotton Worm. 

 Several references have been made in recent 

 issues of the A(jrtraltur<il Xph:s to the cotton worm 

 which has ])roved a troublesonie pest to cotton in 

 Barbados and elsewliere in the West Indies. In the 

 present issue we reprothice from the IfV-s/ radian 

 Bulletin, (Vol. IV, pp. 2G9-71) extracts from Mr. Ballou's 

 account of the life-history of this pest. It will be 

 seen that probably tliree to four days are occupied 

 in the ess stage, that the larval stage takes from 

 one to three weeks, while the insect remains in 

 a dormant state for about a fortnight, the whole 

 generation taking between three and six weeks: — 



The egg: The egg is laid iqion the under side of the 

 younger leaves near the top of the plant. Each feiimle moth 



lays a large luunber of eggs 

 wliich are generally .scattered 

 and rarely, if ever, in clusters. 

 The egg is pale green in 

 colour and quite easily distin- 

 gui.shed ujion the suiface of 

 the leaf. Seen from above, 

 ' / the egg jjresents a circular 

 outline, but viewed from the 

 i.f AMU, ,.,-.^.7-S'de it appears rather ellipti- 

 Z((,-e,;, greatly enlarged :«, dorsal ;Cal, or as if flattened from 

 //, .side" view. above. If it be examined 



with a jiocket len.s, its surface 

 will be seen to be marked with fine lines or ridges 

 radiating from the centre above. The duration of the egg 

 stage in midsummer in the United States is given as three to 

 four days, and in cooler weather slightly longer. 



The larva : "When the young caterpillar first leaves the 

 shell, it is very small and not easily seen, so nearly is it of 

 the colour of the under surface 

 of the leaf, where it remains 

 a short time and begins feeding. 

 At first it does not eat the tissue 

 of the leaf clean but merely 

 gnaws away the under sui'face 

 which is much more tender 

 than the thicker upper surface. 

 As it grows older it eats the 

 entire tissue of the leaf exce}>t 

 only the largest veins. This 

 insect is one of the ' loopers' or 

 'measuring worms.' These names 

 are given because the larva travels 

 by arching its body and bringing 

 uj) its hind legs to the forward 

 ones and then reaching out again 

 to get a new hold with the for- 

 ward pairs. This pecuHarity 

 is shown even in the earliest 

 stages. The development of the 

 cater[>illar requires from one to 

 three week.s, and during this 

 period the skin is shed five times. 

 When first hatched, the larva is 

 yellowish in colour but .soon Larva of Ahfhi inijiJInriH, 

 becomes greenish with numerous enlarged ; actual length indi- 

 black spots and yellowish longi- ''•■'t^l by hair line, 

 tiidinal lines. The fully-grown «, side ; b, dorsal view. 



Cotton \\ orm. 



larva measures nearly li inches and is (juite .slender. The 

 head is dull olive-green ; a very fine bluish-white line extends 

 along the middle of the back the entire length of the body. 

 On either side of this fine line is a wider green line : each of 

 these being, in turn, bordered by a yellow band. There are 

 two rows of black spots along the back — one rr)W in each of 

 the yellow bands — each of the black .spots has a fine stiff 

 hair oi bristle arising from its centre, and careful examination 

 will show a fine white ring outside the black of each spot. 



The sides are olive-green with several more or less 

 interrui)ted lighter lines running lengthwise, the lower one 

 being continuous. There are black sj>ots on the sides also, 

 which are like these on the back except tliat they are 

 smaller, and are not arranged in regular rows. There is 

 much variatif>n in the colour of the larvae at different 

 seasons of the year, the earlier broods being lighter and the 

 ' later ones darker. 



The pupa : When the caterpillar is fulh" grown, it spins 

 a thin, scant cocoon inside which it pujiates. The cocoon 

 usually consists of a few whitish, silken threads, which hold 

 the pujia on the under side of the leaf, the edge of the leaf 

 being fre(piently slightly rolled or drawn under. The i)upa 

 is at first greenish, but .soon becomes dark-brown. It is a 

 little more than .'. inch in length. 



One week to thirty days is the length of time given for 

 the jiujia stage in the United States. Probably in the West 

 Indies the time of [mpation will not extend over more than 

 two weeks on account of the uniformly warm weather. 



The adult insect : The adult or winged in.sect of the 

 cotton caterpillar is a small greyish moth with a spread of 

 wings from IJ to UV inches. There are several fine, wavy, 

 dark lines ruiming across the forewings, and one or two 

 small bluish-white spots in each forewing toward the front. 



The motli is a night-flyer, hiding by day, ami when 

 disturbed. Hying with short, swift darts. At night it flies- 



\ 



Fic. 4. Adult <>{ Alrfii, ar,iilh„-t 

 wings folded, natural resting position . 



wings S[)read; h. 



i.>ut to feetl and lays its eggs. Egg-laying begins a few days 

 after the female leaves the chry.salis and each female lays a 

 laige number of eggs — 300 to -500. Many moths are unable 

 to feed, others merely suck the juices of flowers and 

 fruit ; but this one has a jieculiar prolxiscis with which it is 

 able to jiierce the skin and tissues of ripe fruits, etc., upon 

 which it feeds It also feeds upon the nectar of Howers, etc. 



Further experimental work is still necessary to show 

 how many broods there are in the West Indies, and at what 

 times they appear ; but it is probable that breeding continues 

 all the year round, and that the larger numbers at certain 

 times or .seasons are due to the increased amount of cotton 

 available at those times. Five broods are known to occur 

 each year in the United States. 



The eyes are dark, velvety-brown, large and prominent. 

 Va\\>\ are large and are directed forward and upward in front 

 of the eyes. Between the eyes the long, slender i)roboscis is 

 coiled up like a watch .spring. The antennae are a light, 

 yellowish-grey, long and slender and composed of a large 

 number of small segments. 



