New research revealed that kissing bugs - the bloodsucking insects known to transmit the deadly Chagas disease - feed on plants. This discovery overturns a century old assumption that the bugs feed exclusively on the blood of their victim.

Biologists from Lancaster University in the United Kingdom were inspired to investigate the diet of kissing bugs, also known as assassin bugs, while eating tomatoes for lunch one day.

"I wondered if bloodsucking sandflies in my lab would feed on tomatoes because they are known to like plants," said study researcher Rod Dillon.

After consulting co-researcher Fernando Genta of the Instituto Oswaldo Cruz in Brazil, the theory was extended to kissing bugs. Until now, these Latin American insects were known only for their habit of biting peoples' face or lips at night.

By feeding the insects artificial sugar meals, researchers found they consume sugar and nutrients from fruits of the tomato Solanum lycopersicum. More importantly, researchers found a reduction in the bugs' mortality after ingestion of a blood meal, which dropped from 40 percent to about 20 percent.

"This means they are healthier as they have more energy, can live longer and bite more people," Dillon added.

Furthermore, insects that consumed tomatoes showed greater weight gain after the blood supply, indicating an increase in the volume of blood ingested.

"The discovery adds a new element to kissing bugs' life cycle and will impact knowledge of the transmission of Chagas disease and the control strategies for this disease," Genta explained.

The Centers for Disease Control and Prevention recently reported sightings of kissing bugs in more than half of the states in the U.S., with the most cases in the Carolinas, Georgia and Texas.

Chagas disease, or American trypanosomiasis, is believed to affect eight million people living mainly in the Americas each year. When a person is bitten, swelling generally occurs in one of his or her eyelids.

Additional symptoms include fever, headache, enlarged lymph glands, pallor, muscle pain, difficulty breathing, swelling and abdominal or chest pain. However, it can take years for more serious side effects, such as heart disease, to develop.

Their findings were recently published in the journal Parasites & Vectors.