Small Caterpillars Research Articles

Phoebis philea Linn. in Winter Park, Florida

The following notes on the occurrence of Phoebis philea Linn.1 in Winter Park, Fla. may be of interest, since this locality would appear to be out of its normal range. It seems all the more unusual to have these records when at the same time we have none at all of P. agarithe. All of my records are of individuals seen or caught in my yard in the center of the town, where the butterflies were visiting a young Acacia bush which had reached a size of about 6 ft. high by 6 ft. in diameter when the first one was seen around it. It is now (Jan. 1943) about 8 ft. high and 12 ft. in diameter. I believe that every butterfly seen has been a female; all of those caught have been. The first was captured on Oct. 21, 1941; the second was seen about mid-December 1941 but the exact date is missing. The third was caught on Jan. 4, 1942, and a fourth was seen on April 7th. From May 10th, 1942 until Oct. 10th, I was away from Winter Park. On Oct. 31st another was caught, and one more on Dec. 27. Another was seen on Jan. 17th, 1943 and the most recent one on Jan. 25th. Most of the butterflies have been laying eggs on the bush, but in spite of this I have seen only two very small caterpillars which may have hatched from them and I do not think these survived. At the time of writing this bush has probably 60 eggs on it, presumably from the most recent visitor. Mr. D. F. Berry of Orlando tells me that during the period in which I have seen these he has seen three or four, all apparently females, around Orlando, but has not caught any. He had never seen any previously. I think that the Acacia bush would hardly have been big enough much before the fall of 1941 to attract the butterflies. My work prevents me from keeping the bush under observation. There may well have been 50 visitors of this species in the time under consideration, without my having any chance to see them. Most of the butterflies have lost many of the scales on their wings making their color very pale, but otherwise are in very good condition.

THE BIOLOGY OF PODISUS SERIEVENTRIS UHLER, IN CAPE BRETON, NOVA SCOTIA

The biology of Podisus serieventris Uhler, and its role in an outbreak of the black-headed budworm, Peronea variana Fernald, in Cape Breton, N.S., are described from studies carried on in 1930 and 1931. There is but one complete generation of Podisus a year, and adults of both sexes hibernate. The eggs are laid in late June, July and early August, the incubation period ranging between 10 and 15 days. There are five nymphal stages, requiring about 45 days, on the average, for the attainment of the adult condition. In these respects particularly, the life history of Podisus serieventris in Cape Breton differs from its life history in Massachusetts, where four nymphal stages and three annual generations and the hibernation of females only, have been reported.The species conforms satisfactorily to Dyar's Law, the average growth ratio of individuals studied in 1931 being about 1.28. The first-stage nymphs feed on unhatched eggs of their own species, and upon the juices of coniferous and deciduous foliage, but were not induced to feed upon small caterpillars. Nymphs were able to complete the first instar on a purely vegetable diet, but died before the second moult when the same diet was continued. Older nymphs, fed for some time on animal food, were not able to attain the adult condition when supplied with plant food alone. This indicates the dependence of the species upon animal food; the food consumption of the various stages is briefly summarized. Evidence is presented which suggests the utilization, by Podisus, of a toxic secretion in overcoming their prey.The rather limited value of Podisus as a control factor in the outbreak of Peronea variana in 1930 and 1931 is described. The decline of the Peronea population in 1931 caused a corresponding mortality in the Podisus population, by starvation.

Important Cotton Insects of Central Peru

During a six weeks investigation of cotton insect problems in the Canete Valley, located about 100 miles south of the city of Lima, in central Peru, no evidence was found of the existence in Peru of either the Mexican cotton boll weevil or the pink boll worm. The Peruvian square weevil was found in nearly all fields examined and ranged from sea level to an altitude of over 2,000 feet. This species attacks only small cotton squares and causes them to flare and fall to the ground as do the squares attacked by the boll weevil. The square weevil is a small species, adults measuring from 2.5 to 4 mm. in length. The color is light tan or brownish but the integument under the scale covering is brown. The adults are extremely active and shy and are hard to find in the field but the flaring and falling of squares betray their presence. Usually only six or eight punctured squares occur on a plant but sometimes as many as twenty-five were found, these being apparently the work of one female. The development requires some sixteen or eighteen days and the larvae and pupae in fallen squares appear to be quite resistant to heat and drought. It is not known whether the species can survive freezing temperature during its hibernation period. The most serious cotton pest in Peru seems to be a species of leaf worm. (Possibly more than one species is involved.) This species appears to be native and occurs abundantly every year, requiring usually three poison applications during the season. At least four generations of this leaf worm must occur. The observations made indicated a developmental period of from twenty-two to thirty days. The multiplication is rapid in spite of the presence of a number of species of predators and parasites. The usual method of control has been arsenate of lead or calcium arsenate sprays applied by knapsack spray pumps carried by Indian workmen. These spraying squads often numbering over 100 men, do nothing else for three months but spray for leaf worm control. Their work is very inefficient. Dusting has been started to replace the spraying and has given much better control of the worms with a very great saving in the time and labor of application. The climatic conditions and the topography of the irrigated val1eys are ideal for airplane dusting work and such work is being started this season in Peru. Other important insects include several species of small caterpillars which bore into the developing bolls. Their work is followed by the spread of fungus diseases which complete the destruction of the bolls. By this combined attack a damage of from 20% to 25% of the crop is frequently experienced.

A SERIOUS ATTACK ON THE APPLE FRUIT BY ARGYRESTHIA CONJUGELLA (Zell.) IN EUROPE

In the annual reports of the Canadian Experimental Farms for 1896 and 1897, Dr. James Fletcher describes a new apple-fruit pest in British Columbia, caused by the attacks of small caterpillars, viz., the larvæ of a little tineid moth, Argyresthia conjugella, Zell. The injuries done by this new enemy, called by Mr. Fletcher “the applefruit miner,” closely resemble those caused by the apple maggot, Trypeta pomonella, Walsh. The caterpillars tunnel the pulp of the fruit in every direction, leaving brown-coloured channels with rather large chambers here and there; this attack thus being easily distinguishable from that of the common codling worm.