Fleas

Insects as Weapons or "Bug Bombs"

What are the possibilities? Insects that sting Insects that carry disease Insects that bite/suck Insects that produce toxic substances Affect food supply

World War II Japan and the Pingfan Project Plague and fleas Mass produced (500 million fleas per year). Released fleas from aircraft Also developed other insect-vectored diseases.

Taxonomic classification Phylum: Arthropoda Class: Insecta Order: Siphonaptera Genera: Pulex irritans (human flea) 致痒蚤, 亦称人蚤 Xenopsylla cheopis 印鼠客蚤 Ctenocephalides canis (dog flea) Ctenocephalides felis (cat flea): the most prevalent of all flea species

Host spectrum Canids( 犬科动物 ), felids( 猫科动物 ), humans, calves, opossums( 负鼠 ), chickens, raccoons( 浣熊 )(best found on cats, stray dogs and mongoose 猫鼬 ) Host preferential rather than host specific

Geographic distribution Worldwide - survive best in humid conditions (90% humidity).

Morphology Adults to 4 mm long, dark brown, laterally flattened, wingless, piercing- sucking mouthparts, genal (on the cheek) and pronotal (on the posterior border of the 1st thoracic segment) combs (ctenidia), rounded head

雌蚤

蚤头部及前胸

致痒蚤 （ Pulex irritans ） 亦称人蚤，在眼下方 有眼鬃毛 1 根；受精 囊的头部圆形，尾部 细长弯曲 印鼠客蚤 Xenopsylla cheopis 眼鬃毛 1 根，位于眼 的前方；受精囊的头 部与尾部宽度相近， 且大部分呈暗色

Eggs - about 0.5 mm long, oval, pearly white (nonfertile females will produce eggs, but they will be nonviable)

Larvae - about 6 mm long, maggot-like, creamy-yellow, 13 segments with bristles on each

Pupae - with a loosely woven cocoon which collects debris, about 4 x 2 mm

Life cycle

Life cycle (stages) Eggs are laid in the host‘s bed, den 兽穴, etc. (called environmental hot spots); or laid on the host, where they fall off easily because they are not sticky. Larvae feed on dry blood, feces, etc. and may remain in this stage as long as 200 days.

Pupal stage is the most tolerant stage and can last from 10 days up to 50 weeks as pre-emergent adult, depending on environmental conditions Pre-emergent adults are stimulated to emerge by heat, carbon dioxide, movement (human or pet activity). Without stimuli, emergence will be delayed. Life cycle takes an average of days but may take 20 months or more.

Habits Life span of adult: 1 year, several months when unfed. Breeding places: Eggs are laid in hosts’nest or even hair. Feeding: The larvae take adult fleas’ feces and other organic debris as their food. Both male and female adults are blood suckers. They have relative blood preference.

Habits Thermo-tropism: Fleas prefer warmth. Seasonal distribution: Majority are prevalent from May to October. Activity: They may jump as far as cm and as high as 20 cm, but their jumping is not directional. The transmission of flea is performed only by their host.

Fleas and Diseases Causes irritation, scratching, restlessness Vector of Yersinia pestis (plague) Endemic typhus or flea-borne typhus. Intermediate hosts of some tape-worm: Dipylidium caninum, Hymenolepis nana.

Control Eradication of rodents. Eradication of fleas by burning, chemicals. Personal hygiene, rat-proof buildings, and do not let dogs and cats come into the houses.